Relevant bibliographies by topics / Two sample testing

Academic literature on the topic 'Two sample testing'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Two sample testing.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Two sample testing"

1

Städler, Nicolas, and Sach Mukherjee. "Two-sample testing in high dimensions." Journal of the Royal Statistical Society: Series B (Statistical Methodology) 79, no. 1 (April 9, 2016): 225–46. http://dx.doi.org/10.1111/rssb.12173.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Holmes, Chris C., François Caron, Jim E. Griffin, and David A. Stephens. "Two-sample Bayesian Nonparametric Hypothesis Testing." Bayesian Analysis 10, no. 2 (June 2015): 297–320. http://dx.doi.org/10.1214/14-ba914.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Tsong, Yi, and Wen-Jen Chen. "Noninferiority Testing Beyond Simple Two-Sample Comparison." Journal of Biopharmaceutical Statistics 17, no. 2 (February 23, 2007): 289–308. http://dx.doi.org/10.1080/10543400601177368.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Ramsey, Philip, and Patricia Ramsey. "Testing Variability in the Two-Sample Case." Communications in Statistics - Simulation and Computation 36, no. 2 (2007): 233–48. http://dx.doi.org/10.1080/03610910601158310.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Gillam, T. P. S., and C. G. Lester. "Biased bootstrap sampling for efficient two-sample testing." Journal of Instrumentation 13, no. 12 (December 10, 2018): P12014. http://dx.doi.org/10.1088/1748-0221/13/12/p12014.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Gönen, Mithat, Peter H. Westfall, and Wesley O. Johnson. "Bayesian Multiple Testing for Two-Sample Multivariate Endpoints." Biometrics 59, no. 1 (March 2003): 76–82. http://dx.doi.org/10.1111/1541-0420.00009.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Liu, Yukun, Pengfei Li, and Yuejiao Fu. "Testing Homogeneity in a Semiparametric Two-Sample Problem." Journal of Probability and Statistics 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/537474.

Full text
Abstract:
We study a two-sample homogeneity testing problem, in which one sample comes from a population with densityf(x)and the other is from a mixture population with mixture density(1−λ)f(x)+λg(x). This problem arises naturally from many statistical applications such as test for partial differential gene expression in microarray study or genetic studies for gene mutation. Under the semiparametric assumptiong(x)=f(x)eα+βx, a penalized empirical likelihood ratio test could be constructed, but its implementation is hindered by the fact that there is neither feasible algorithm for computing the test statistic nor available research results on its theoretical properties. To circumvent these difficulties, we propose an EM test based on the penalized empirical likelihood. We prove that the EM test has a simple chi-square limiting distribution, and we also demonstrate its competitive testing performances by simulations. A real-data example is used to illustrate the proposed methodology.
APA, Harvard, Vancouver, ISO, and other styles
8

Ghoshdastidar, Debarghya, Maurilio Gutzeit, Alexandra Carpentier, and Ulrike von Luxburg. "Two-sample hypothesis testing for inhomogeneous random graphs." Annals of Statistics 48, no. 4 (August 2020): 2208–29. http://dx.doi.org/10.1214/19-aos1884.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Feng, Shixia, Qiwei Liang, Robin D. Kinser, Kirk Newland, and Rudolf Guilbaud. "Testing equivalence between two laboratories or two methods using paired-sample analysis and interval hypothesis testing." Analytical and Bioanalytical Chemistry 385, no. 5 (June 7, 2006): 975–81. http://dx.doi.org/10.1007/s00216-006-0417-2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Zhu, Shengyu, Biao Chen, Zhitang Chen, and Pengfei Yang. "Asymptotically Optimal One- and Two-Sample Testing With Kernels." IEEE Transactions on Information Theory 67, no. 4 (April 2021): 2074–92. http://dx.doi.org/10.1109/tit.2021.3059267.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Two sample testing"

1

Tong, Bo. "More accurate two sample comparisons for skewed populations." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/35783.

Full text
Abstract:
Doctor of Philosophy
Department of Statistics
Haiyan Wang
Various tests have been created to compare the means of two populations in many scenarios and applications. The two-sample t-test, Wilcoxon Rank-Sum Test and bootstrap-t test are commonly used methods. However, methods for skewed two-sample data set are not well studied. In this dissertation, several existing two sample tests were evaluated and four new tests were proposed to improve the test accuracy under moderate sample size and high population skewness. The proposed work starts with derivation of a first order Edgeworth expansion for the test statistic of the two sample t-test. Using this result, new two-sample tests based on Cornish Fisher expansion (TCF tests) were created for both cases of common variance and unequal variances. These tests can account for population skewness and give more accurate test results. We also developed three new tests based on three transformations (T[subscript i] test, i = 1; 2; 3) for the pooled case, which can be used to eliminate the skewness of the studentized statistic. In this dissertation, some theoretical properties of the newly proposed tests are presented. In particular, we derived the order of type I error rate accuracy of the pooled two-sample t-test based on normal approximation (TN test), the TCF and T[subscript i] tests. We proved that these tests give the same theoretical type I error rate under skewness. In addition, we derived the power function of the TCF and TN tests as a function of the population parameters. We also provided the detailed conditions under which the theoretical power of the two-sample TCF test is higher than the two-sample TN test. Results from extensive simulation studies and real data analysis were also presented in this dissertation. The empirical results further confirm our theoretical results. Comparing with commonly used two-sample parametric and nonparametric tests, our new tests (TCF and Ti) provide the same empirical type I error rate but higher power.
APA, Harvard, Vancouver, ISO, and other styles
2

Taneja, Atrayee. "New approaches to testing a composite null hypothesis for the two sample binomial problem /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487323583622319.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Noordien, Zorina. "Testing two measures of subjective well-being amongst a sample of children in the Western Cape." University of the Western Cape, 2015. http://hdl.handle.net/11394/4163.

Full text
Abstract:
Magister Artium - MA
Recent advancements in child well-being research have shown an increased interest in the importance of subjective well-being. The development of instruments and scales to measure subjective well-being among children and adolescents is in its infancy. Furthermore, there are few existing cross-cultural studies with child and adolescent populations. Validation of existing measures and cross-cultural comparisons has been identified by a number of researchers as critical in contributing to the international dialogue. In the current study, two measures of subjective well-being (Student Life Satisfaction Scale and Personal Well-Being Index-School Children) are tested among a sample of children in the Western Cape region of South Africa. Noting the diversity of experience between children from different socio-economic status groups in South Africa, the study further aims to determine the extent to which the measures are comparable across socio-economic status groups. Data from the Children’s World Survey were used; and includes a sample of 1004 children randomly selected from 15 schools within the Cape Town Metropole. Confirmatory factor analysis was used to test the overall fit structure and multi-group factor analysis, with Scalar and Metric invariance constraints. The results show appropriate fit structure for the overall model, with Scalar and Metric factor invariance tenable across socio-economic status groups. The overall findings suggest that the two measures are appropriate for use with children from low and medium socio-economic status groups in the Western Cape province of South Africa.
APA, Harvard, Vancouver, ISO, and other styles
4

Atta-Asiamah, Ernest. "Distributed Inference for Degenerate U-Statistics with Application to One and Two Sample Test." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31777.

Full text
Abstract:
In many hypothesis testing problems such as one-sample and two-sample test problems, the test statistics are degenerate U-statistics. One of the challenges in practice is the computation of U-statistics for a large sample size. Besides, for degenerate U-statistics, the limiting distribution is a mixture of weighted chi-squares, involving the eigenvalues of the kernel of the U-statistics. As a result, it’s not straightforward to construct the rejection region based on this asymptotic distribution. In this research, we aim to reduce the computation complexity of degenerate U-statistics and propose an easy-to-calibrate test statistic by using the divide-and-conquer method. Specifically, we randomly partition the full n data points into kn even disjoint groups, and compute U-statistics on each group and combine them by averaging to get a statistic Tn. We proved that the statistic Tn has the standard normal distribution as the limiting distribution. In this way, the running time is reduced from O(n^m) to O( n^m/km_n), where m is the order of the one sample U-statistics. Besides, for a given significance level , it’s easy to construct the rejection region. We apply our method to the goodness of fit test and two-sample test. The simulation and real data analysis show that the proposed test can achieve high power and fast running time for both one and two-sample tests.
APA, Harvard, Vancouver, ISO, and other styles
5

Sun, Yiping. "Rank-sum test for two-sample location problem under order restricted randomized design." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180147276.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Boulet, John R. "A Monte Carlo comparison of the Type I error rates of the likelihood ratio chi-square test statistic and Hotelling's two-sample T2 on testing the differences between group means." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5708.

Full text
Abstract:
The present paper demonstrates how Structural Equation Modelling (SEM) can be used to formulate a test of the difference in means between groups on a number of dependent variables. A Monte Carlo study compared the Type I error rates of the Likelihood Ratio (LR) Chi-square ($\chi\sp2$) statistic (SEM test criterion) and Hotelling's two-sample T$\sp2$ statistic (MANOVA test criterion) in detecting differences in means between two independent samples. Seventy-two conditions pertaining to average sample size ((n$\sb1$ + n$\sb2$)/2), extent of inequality of sample sizes (n$\sb1$:n$\sb2$), number of variables (p), and degree of inequality of variance-covariance matrices ($\Sigma\sb1$:$\Sigma\sb2$) were modelled. Empirical sampling distributions of the LR $\chi\sp2$ statistic and Hotelling's T$\sp2$ statistic consisted fo 2000 samples drawn from multivariate normal parent populations. The actual proportion of values that exceeded the nominal levels are presented. The results indicated that, in terms of maintaining Type I error rates that were close to the nominal levels, the LR $\chi\sp2$ statistic and Hotelling's T$\sp2$ statistic were comparable when $\Sigma\sb1$ = $\Sigma\sb2$ and (n$\sb1$ + n$\sb2$)/2:p was relatively large (i.e., 30:1). However, when $\Sigma\sb1$ = $\Sigma\sb2$ and (n$\sb1$ + n$\sb2$)/2:p was small (i.e., 10:1) Hotelling's T$\sp2$ statistic was preferred. When $\Sigma\sb{1} \not=\Sigma\sb2$ the LR $\chi\sp2$ statistic provided more appropriate Type I error rates under all of the simulated conditions. The results are related to earlier findings, and implications for the appropriate use of the SEM method of testing for group mean differences are noted.
APA, Harvard, Vancouver, ISO, and other styles
7

Yeo, Jiyoun. "A Multiplex Two-Color Real-Time PCR Method for Quality-Controlled Molecular Diagnostic Testing of FFPE Samples." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1396507223.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Harbour, Kenton Dean. "A data acquisition system with switched capacitor sample-and-hold." Thesis, Kansas State University, 1986. http://hdl.handle.net/2097/15269.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Jung, Wooseok. "Polymer Lab-on-a-chips from Micro Blood Sampling to Immunoassay for Point-of-care testing of Neonates and Pediatrics in Intensive Care Unit." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378197139.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Lee, Kang Kug. "A Sample-to-Answer Polymer Lab-on-a-Chip with Superhydrophilic Surfaces using a Spray Layer-by-Layer Nano-Assembly Method." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384864905.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Two sample testing"

1

Levchenko, Boris. Criteria for testing hypotheses about uniformity. Application manual. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/986695.

Full text
Abstract:
The guide discusses the use of statistical criteria focused on the testing of hypotheses about uniformity of laws, which belong to the analyzed sample, of the homogeneous medium (about equality of the mathematical expectations), about the homogeneity of variance (equality of variances of compared samples). The disadvantages and advantages of various criteria are indicated, and the application of criteria in conditions of violation of standard assumptions is considered. Tables containing percentage points and statistical distribution models necessary for the correct application of the criteria are provided. This publication describes a broader set of criteria. Constructed models of marginal distributions of statistics for some sample criteria of law uniformity are proposed. Following the recommendations will ensure the correctness and validity of statistical conclusions when analyzing data. It is intended for specialists who are more or less faced with the issues of statistical data analysis, processing the results of experiments, and using statistical methods to analyze various aspects and trends of the surrounding reality. It will be useful for engineers, researchers, specialists in various fields (doctors, biologists, sociologists, economists, etc.), University teachers, graduate students and students.
APA, Harvard, Vancouver, ISO, and other styles
2

Lemeshko, Boris, and Irina Veretel'nikova. Criteria for testing hypotheses about randomness and the absence of a trend. Application Guide. ru: INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1587437.

Full text
Abstract:
The monograph discusses the application of statistical criteria aimed at testing hypotheses about the absence of a trend in the analyzed samples. The rejection of such a hypothesis gives grounds to consider the analyzed data as samples of independent equally distributed random variables. We consider a set of special criteria aimed at testing such hypotheses, as well as a set of criteria for the uniformity of laws, the uniformity of averages and the uniformity of variances, which can also be used for these purposes. The disadvantages and advantages of various criteria are emphasized, the application of criteria in conditions of violation of standard assumptions is considered. Estimates of the power of the criteria are given, which allows you to navigate when choosing the most preferred criteria. Following the recommendations will ensure the correctness and increase the validity of statistical conclusions when analyzing data. It is intended for specialists who are interested in the application of statistical methods for the analysis of various aspects and trends of the surrounding reality and who are in contact with the processing of experimental results, the need for data analysis in their activities. It will be useful for engineers, researchers, specialists of various profiles (doctors, biologists, sociologists, economists, etc.) who face the need for statistical analysis of experimental results in their activities. It will also be useful for university teachers, graduate students and students.
APA, Harvard, Vancouver, ISO, and other styles
3

Paliy, Irina. Probability theory and mathematical statistics. ru: INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1065828.

Full text
Abstract:
The tutorial is an introductory course in probability theory and mathematical statistics. Elements of combinatorics, basic concepts and theorems of probability theory, discrete random variables, continuous random variables, some limit theorems, one-dimensional and two-dimensional samples, point and interval estimation of parameters of the general population, testing of statistical hypotheses, elements of queuing theory are considered. The presentation of the theoretical material is accompanied by a large number of detailed examples of problem solving. For students of technical and economic fields of study and specialties, studying under the bachelor's and specialty programs.
APA, Harvard, Vancouver, ISO, and other styles
4

Lemeshko, Boris, and Pavel Blinov. Criteria for checking deviations from the exponential law. Application manual. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1097477.

Full text
Abstract:
The monograph is intended for specialists who are more or less faced with the issues of statistical data analysis, processing of experimental results, and using statistical methods to analyze various aspects and trends of the surrounding reality. The guide discusses the application of statistical criteria aimed at testing the hypothesis that the analyzed sample belongs to the exponential (exponential) distribution law. The disadvantages and advantages of various criteria are indicated. Estimates of the power of the criteria and results of comparative analysis of the criteria are given, as well as tables containing percentage points and statistical distribution models necessary for applying the criteria. Following the recommendations will ensure the correctness and validity of statistical conclusions when analyzing data. It will be useful for engineers, researchers, specialists in various fields (doctors, biologists, sociologists, economists, etc.) who are faced with the need for statistical analysis of experimental results, as well as University teachers, graduate students and students.
APA, Harvard, Vancouver, ISO, and other styles
5

Lin, Wen-Ying. Robustness of two multivariate tests to variance-covariance heteroscedasticity and nonnormality when total-sample-size-to-variable ratio is small. 1991.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Morgan, Douglas E. Point-of-Care Testing (DRAFT). Edited by Raghavan Murugan and Joseph M. Darby. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190612474.003.0030.

Full text
Abstract:
Point-of-care testing (POCT) is defined as medical diagnostic testing performed outside the clinical laboratory in close proximity to where the patient is receiving care. POCT is typically performed by non-laboratory personnel and the results are used for clinical decision making. When used appropriately, point-of-care testing (POCT) is a valuable resource during the rapid response system (RRS) activation. Advantages include shortened time between acquiring a sample from the patient and analysis of that sample and a subsequent decrease in time to clinical decision making. Disadvantages revolve largely around the cost of POCT. Driving forces behind the movement towards POCT include care process optimization, improvement of patient outcomes, changing regulatory requirements, and changes in the face of the workforce.
APA, Harvard, Vancouver, ISO, and other styles
7

Cai, Zongwu. Functional Coefficient Models for Economic and Financial Data. Edited by Frédéric Ferraty and Yves Romain. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780199568444.013.6.

Full text
Abstract:
This article discusses the use of functional coefficient models for economic and financial data analysis. It first provides an overview of recent developments in the nonparametric estimation and testing of functional coefficient models, with particular emphasis on the kernel local polynomial smoothing method, before considering misspecification testing as an important econometric question when fitting a functional (varying) coefficient model or a trending time-varying coefficient model. It then describes two major real-life applications of functional coefficient models in economics and finance: the first deals with the use of functional coefficient instrumental-variable models to investigate the empirical relation between wages and education in a random sample of young Australian female workers from the 1985 wave of the Australian Longitudinal Survey, and the second is concerned with the use of functional coefficient beta models to analyze the common stock price of Microsoft stock (MSFT) during the year 2000 using the daily closing prices.
APA, Harvard, Vancouver, ISO, and other styles
8

Arce, Michael. Laboratory Testing for Microbial Detection. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199976805.003.0001.

Full text
Abstract:
The approach to microbial detection in patients who present to acute settings should be focused and should aim to result in clinically significant findings while minimizing the chances of a missed diagnosis or missed complications related to a patient’s existing disease burden. Judicious selection of laboratory tests, efficient sample collection, and laboratory reporting are all important considerations. This chapter provides general guidelines for the initial evaluation of potential microbial infections in patients presenting to the Emergency Department (ED). In some cases, the diagnosis will remain uncertain during the patient’s stay, but diagnostic testing initiated in the ED may be beneficial for the inpatient or outpatient team and the future care of the patient.
APA, Harvard, Vancouver, ISO, and other styles
9

Miksza, Peter, and Kenneth Elpus. Inferential Analysis. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199391905.003.0005.

Full text
Abstract:
Researchers often employ statistical techniques to test hypotheses and to express the relative certainty they have when making a claim about how statistics derived from their sample data might be representative of population parameters. This chapter illustrates the logic underlying inferential statistical tests. Inferential analyses involves a set of tools that music education researchers can use when posing scientific questions and seeking to refute their hypotheses. The chapter describes techniques that can be used for testing hypotheses and estimating population parameters on the basis of sample data. In doing so, the chapter emphasizes basic approaches to null hypothesis significance testing, interpreting effect sizes, and building confidence intervals. The chapter also provides a brief critique of null hypothesis significance testing as a tradition.
APA, Harvard, Vancouver, ISO, and other styles
10

Kotzer, Katrina E., and Sarah E. Kerr. Molecular Technologies and Test Issues. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190604929.003.0005.

Full text
Abstract:
Molecular genetic testing has been around since the discovery and offering of clinical testing for the first gene sequenced. However, in recent years the methods and scope of molecular genetic testing have evolved significantly to encompass next-generation sequencing, multigene panels, and whole exome and genome testing. With this evolution in molecular methods, the nomenclature and variant evaluation and annotation processes are crucial for the systematic and standard interpretation of molecular test results. This chapter will provide the laboratory genetic counselor with information about the common sample types analyzed by molecular techniques for the purposes of genetic testing and the various methodologies available and their limitations. Guidelines are given for the standard approach to molecular variant reporting with respect to nomenclature and variant classification.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Two sample testing"

1

Kolassa, John E. "Two-Sample Testing." In An Introduction to Nonparametric Statistics, 39–67. First edition. | Boca Raton : CRC Press, 2020. |: Chapman and Hall/CRC, 2020. http://dx.doi.org/10.1201/9780429202759-3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Goodman, Melody S. "Two-Sample Hypothesis Testing." In Biostatistics for Clinical and Public Health Research, 221–54. Milton Park, Abingdon, Oxon ; New York, NY : Routledge, 2018.: Routledge, 2017. http://dx.doi.org/10.4324/9781315155661-12.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Scharwächter, Erik, and Emmanuel Müller. "Two-Sample Testing for Event Impacts in Time Series." In Proceedings of the 2020 SIAM International Conference on Data Mining, 10–18. Philadelphia, PA: Society for Industrial and Applied Mathematics, 2020. http://dx.doi.org/10.1137/1.9781611976236.2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Goodman, Melody S. "Lab D: Two-sample (parametric and nonparametric) hypothesis testing." In Biostatistics for Clinical and Public Health Research, 281–87. Milton Park, Abingdon, Oxon ; New York, NY : Routledge, 2018.: Routledge, 2017. http://dx.doi.org/10.4324/9781315155661-14.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Hedberg, E. C. "Using Covariates When Testing the Difference in Sample Group Means for Balanced Designs." In Introduction to Power Analysis: Two-Group Studies, 54–70. 2455 Teller Road, Thousand Oaks California 91320: SAGE Publications, Inc., 2018. http://dx.doi.org/10.4135/9781506343105.n9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Aldridge, Matthew, and David Ellis. "Pooled Testing and Its Applications in the COVID-19 Pandemic." In Springer Actuarial, 217–49. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78334-1_11.

Full text
Abstract:
AbstractWhen testing for a disease such as COVID-19, the standard method is individual testing: we take a sample from each individual and test these samples separately. An alternative is pooled testing (or ‘group testing’), where samples are mixed together in different pools, and those pooled samples are tested. When the prevalence of the disease is low and the accuracy of the test is fairly high, pooled testing strategies can be more efficient than individual testing. In this chapter, we discuss the mathematics of pooled testing and its uses during pandemics, in particular the COVID-19 pandemic. We analyse some one- and two-stage pooling strategies under perfect and imperfect tests, and consider the practical issues in the application of such protocols.
APA, Harvard, Vancouver, ISO, and other styles
7

Schlag, Mareike, Kai Brune, Hauke Brüning, Michael Noeske, Célian Cherrier, Tobias Hanning, Julius Drosten, et al. "Extended Non-destructive Testing for Surface Quality Assessment." In Adhesive Bonding of Aircraft Composite Structures, 119–222. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-319-92810-4_3.

Full text
Abstract:
AbstractThis chapter introduces various extended non-destructive testing (ENDT) techniques for surface quality assessment, which are first characterized, then enhanced, and finally applied to assess the level of pre-bond contaminations intentionally applied to carbon fiber reinforced plastic (CFRP) adherends following the procedures described in the previous chapter. Based on two user cases comprising different scenarios that are characteristic of either aeronautical production or repair, the detailed tests conducted on two types of sample geometry, namely flat coupons and scarfed pilot samples with a more complex shape, form the basis for applying the advanced ENDT procedures for the monitoring of realistic and real aircraft parts, as will be described in Chap. 10.1007/978-3-319-92810-4_5. Specifically, the reported investigations were performed to assess the surface quality of first ground and then intentionally contaminated CFRP surfaces using the following ENDT tools: the aerosol wetting test (AWT), optically stimulated electron emission (OSEE), two differently implemented approaches based on electronic noses, laser-induced breakdown spectroscopy (LIBS), Fourier-transform infrared (FTIR) spectroscopy, laser-induced fluorescence (LIF), and laser vibrometry.
APA, Harvard, Vancouver, ISO, and other styles
8

Chernoff, Herman. "Conservative bounds on extreme P-values for testing the equality of two probabilities based on very large sample sizes." In Institute of Mathematical Statistics Lecture Notes - Monograph Series, 250–54. Beachwood, Ohio, USA: Institute of Mathematical Statistics, 2004. http://dx.doi.org/10.1214/lnms/1196285395.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Ortlepp, Regine, Christoph Schünemann, Patrycia Brzoska, David Schiela, Janneke Westermann, Benjamin Richter, Stefanie Kunze, and Heidi Sinning. "Building Heat-Resilient Neighborhoods—Testing the Implementation on Buildings and in Open Spaces in Two Sample Quarters Dresden and Erfurt." In Building Resilience to Natural Hazards in the Context of Climate Change, 113–56. Wiesbaden: Springer Fachmedien Wiesbaden, 2021. http://dx.doi.org/10.1007/978-3-658-33702-5_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Caulcutt, Roland. "Testing and estimation: two samples." In Statistics in Research and Development, 66–80. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4899-2943-3_5.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Two sample testing"

1

Deng, Alex. "Objective Bayesian Two Sample Hypothesis Testing for Online Controlled Experiments." In WWW '15: 24th International World Wide Web Conference. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2740908.2742563.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Deng, Alex. "Objective Bayesian Two Sample Hypothesis Testing for Online Controlled Experiments." In WWW '15: 24th International World Wide Web Conference. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2740908.2743062.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Kipnis, Alon, and David L. Donoho. "Two-sample Testing of Discrete Distributions under Rare/Weak Perturbations." In 2021 IEEE International Symposium on Information Theory (ISIT). IEEE, 2021. http://dx.doi.org/10.1109/isit45174.2021.9517991.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Bargiotas, Ioannis, Argyris Kalogeratos, Myrto Limnios, Pierre-Paul Vidal, Damien Ricard, and Nicolas Vayatis. "Multivariate two-sample hypothesis testing through AUC maximization for biomedical applications." In SETN 2020: 11th Hellenic Conference on Artificial Intelligence. New York, NY, USA: ACM, 2020. http://dx.doi.org/10.1145/3411408.3411422.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Rastogi, Charvi, Sivaraman Balakrishnan, Nihar Shah, and Aarti Singh. "Two-Sample Testing on Pairwise Comparison Data and the Role of Modeling Assumptions." In 2020 IEEE International Symposium on Information Theory (ISIT). IEEE, 2020. http://dx.doi.org/10.1109/isit44484.2020.9174055.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Gangrade, Aditya, Bobak Nazer, and Venkatesh Saligrama. "Two-Sample Testing can be as Hard as Structure Learning in Ising Models: Minimax Lower Bounds." In ICASSP 2018 - 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). IEEE, 2018. http://dx.doi.org/10.1109/icassp.2018.8462370.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

GONZALEZ-ROMA, VICENTE, ANA HERNANDEZ, JUAN PABLO GAMBOA, and INES TOMAS. "Social class and university graduates’ overqualification: testing two mediated relationships." In Fourth International Conference on Higher Education Advances. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/head18.2018.8035.

Full text
Abstract:
University graduates’ overqualification (i.e., having more education, qualification and/or skills than one’s job requires) has important negative consequences. However, much less is known about its antecedents. This represents an important gap in the literature. In order to fill this gap, the goal of this study is to test a mediational model on the antecedents of university graduates’ overqualification (OQ). We posit that social class is negatively related to OQ through two mediational links: a) via social capital, and b) via social capital and tolerance towards OQ. The results obtained in a sample of 144 university graduates provided support for the second mediational link, so that social class was positively related to social capital, which in turn was negatively related to tolerance towards OQ, which in turn was positively related to graduates’ OQ. The results obtained uncover some of the antecedents of OQ and suggest that increasing social capital may be a way to decrease graduates’ OQ.
APA, Harvard, Vancouver, ISO, and other styles
8

Philonenko, Petr, and Sergey Postovalov. "Test power in two-sample problem testing as the utility function in the theory of decision making under risk and uncertainty." In 2016 13th International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE). IEEE, 2016. http://dx.doi.org/10.1109/apeie.2016.7806491.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Philonenko, P. A., and S. N. Postovalov. "Test power in two-sample problem testing as the utility function in the theory of decision making under risk and uncertainty." In 2016 13th International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE). IEEE, 2016. http://dx.doi.org/10.1109/apeie.2016.7806956.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Sayers, Michael B., and Tara M. Dalton. "A Novel Contamination Free Two Temperature Continuous Flow Polymerase Chain Reactor." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43055.

Full text
Abstract:
Polymerase Chain Reaction (PCR) is an enzymatic process that has dramatically advanced many fields of life sciences, where it is an indispensable tool in a burgeoning range of applications, including diagnostic medicine, molecular biology, forensics and food testing. Recent increased demand for extremely high throughput PCR systems has led to the development of miniaturised continuous flow microfluidic PCR devices, which may have extremely high throughput compared to standard commercial PCR thermal cyclers. A novel continuous flow microfluidic PCR device has been designed and fabricated, consisting of two thermal zones maintained on aluminium thermal blocks providing the precise temperatures required for denaturation and annealing/extension. Polycarbonate sideplates retain the denaturation thermal block vertically above the annealing/extension thermal block while allowing for a variable air gap to be maintained between them. Heating of the denaturation thermal block is achieved using a Labview controlled Thermofoil heater, while the annealing/extension thermal block is maintained at temperature by optimised heat transfer from the denaturation block. Flow-through capillary tubing is positioned into a grooved serpentine channel machined into these thermal blocks. This serpentine channel passes through each thermal block fifty times, providing fifty PCR thermal cycles. Contamination free high throughput continuous flow PCR necessitates that the samples be encapsulated in an immiscible carrier fluid to eradicate cross contamination between samples and suppress the likelihood of the sample contacting the capillary leading to sample degradation. Encapsulation of the PCR reaction mixture is achieved upstream of the thermal cycler through segmentation of the sample into droplets entrained within an immiscible carrier fluid, which are then cycled through the thermal cycler. High throughput DNA amplification of two genes, GAPDH and LEF1, from the REH cell line has been successfully demonstrated on this microfluidic platform without any detectable contamination between samples. The PCR droplet reactors were approximately 250nl which is two orders of magnitude less than the standard sample size for most commercial PCR thermal cyclers.
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Two sample testing"

1

Friedman, J. On Multivariate Goodness-of-Fit and Two-Sample Testing. Office of Scientific and Technical Information (OSTI), January 2004. http://dx.doi.org/10.2172/826696.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Montalvo-Bartolomei, Axel, Bryant Robbins, Erica Medley, and Benjamin Breland. Backward erosion testing : Magnolia Levee. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42140.

Full text
Abstract:
Using a confined flume device, an experimental study investigated the critical horizontal gradient of soils obtained from a site identified as potentially vulnerable to backward erosion piping (BEP). Tests were conducted on glacial outwash material obtained from a sand and gravel quarry in the vicinity of Magnolia Levee in the community of Magnolia, OH. The two bulk samples collected from the quarry had similar grain-size distributions, grain roundness, and depositional environments as the foundation materials beneath the levee. Samples were prepared at various densities and subjected to gradual increases of flow in a wooden flume with an acrylic top until BEP was observed. The critical average horizontal gradient ranged from 0.21 to 0.30 for a bulk sample with a coefficient of uniformity of 1.6, while tests conducted on a bulk sample with a coefficient of uniformity of 2.5 yielded critical average horizontal gradients of 0.31 to 0.36. The critical average gradients measured during these tests compared favorably to values in the literature after applying adjustments according to Schmertmann’s method.
APA, Harvard, Vancouver, ISO, and other styles
3

Boehm, Ted W., and Jim Handy. Central HMA Acceptance Lab Process Improvement Implementation Plan Project. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317130.

Full text
Abstract:
The Indiana Department of Transportation (INDOT) Central Hot Mix Asphalt (HMA) Acceptance Lab was opened on March 29, 2018 at the Office of Materials Management (OMM) facility in Indianapolis. The state-of-the-art lab conducts acceptance testing on HMA samples from INDOT’s Crawfordsville and Greenfield districts, as well as testing of appeals samples from the other four INDOT districts. Each HMA sample undergoes multiple sequences acceptance testing processes. In 2019, project SPR-4353 “Central HMA Acceptance Lab Process Improvement Project” was conducted with the goal to improve organization, flow of work and efficiency in the central region HMA Acceptance Lab for all tests done, and provide implementation leading to the reduction of turnaround time from six days to four days. This project follows key recommended actions from SPR-4353 to implementation.
APA, Harvard, Vancouver, ISO, and other styles
4

Science, Fera. Analysis of CBD Products. Food Standards Agency, November 2022. http://dx.doi.org/10.46756/sci.fsa.cis490.

Full text
Abstract:
The Food Standards Agency commissioned Fera Science Ltd. to carry out a survey to obtain a snapshot of CBD products on sale in England and Wales in order to inform FSA risk assessment of CBD products. Thirty CBD products were purchased from a range of online sellers from England and Wales. Samples comprised of two broad categories: oils and sprays, and edibles (including beverages). The sampling followed a scheme suggested by FSA. This is not a statistically representative sample of the market and instead provides a snapshot of the current market, to assist the design of future sampling and surveillance activity. There is the potential for residues of chemicals to be present in CBD products as a result of their natural occurrence in the raw material or arising from the manufacturing process, for example, mycotoxins, metals, pesticides, and the residues of solvents used to extract CBD. This study informs the FSA’s understanding of the type and levels of contaminants that may arise in CBD products. A wide range of analysis on CBD products was undertaken using accredited methods, for heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), pesticides, mycotoxins, CBD content and cannabinoid profiles. Analysis for residual solvents and additional mycotoxins was also carried out, but these were not accredited. The results of testing found the following: Heavy metals (cadmium, mercury & lead) and arsenic were not detected in the majority of samples, meaning levels were below the limits of quantification of the method. Seven samples contained lead, four samples arsenic and two samples contained cadmium. Mercury was not found in any sample. A definitive statement as to whether products exceed maximum levels cannot be made due to uncertainty as to whether products would be classified as a food (i.e. oil) or a food supplement. A low incidence of low levels of mycotoxins, with Fusarium mycotoxins found more frequently than aflatoxins and ochratoxin A, mostly at the methods reporting limit. Three samples were found to contain ochratoxin A at the methods reporting limit. A total of seven pesticide residues were found across all of the products (each product was tested for over 400 pesticides). There are no specific Maximum Residue Limits (MRL) for CBD products. One oil product was found to have PAHs above the regulated levels, if classed as a product for direct consumption. If classed as a food supplement the PAHs were within regulated levels. Three samples contained residual solvents. One product was over the MRL. Most products contained CBD close to the declared value. Two oils had substantially different levels than that declared (one higher and one lower). CBD was not detected in one of the drink products. These are potentially non-compliant with compositional and standards requirements. Delta 9-THC was detected in 87 % (26) of the samples analysed. Of these 40% (12) were found to have THC+ (the total sum of illicit cannabinoids in the product) above the 1mg threshold outlined in current Home Office guidance (Opens in a new window).
APA, Harvard, Vancouver, ISO, and other styles
5

Willis, C., F. Jorgensen, S. A. Cawthraw, H. Aird, S. Lai, M. Chattaway, I. Lock, E. Quill, and G. Raykova. A survey of Salmonella, Escherichia coli (E. coli) and antimicrobial resistance in frozen, part-cooked, breaded or battered poultry products on retail sale in the United Kingdom. Food Standards Agency, May 2022. http://dx.doi.org/10.46756/sci.fsa.xvu389.

Full text
Abstract:
Frozen, breaded, ready-to-cook chicken products have been implicated in outbreaks of salmonellosis. Some of these outbreaks can be large. For example, one outbreak of Salmonella Enteritidis involved 193 people in nine countries between 2018 and 2020, of which 122 cases were in the UK. These ready-to-cook products have a browned, cooked external appearance, which may be perceived as ready-to-eat, leading to mishandling or undercooking by consumers. Continuing concerns about these products led FSA to initiate a short-term (four month), cross-sectional surveillance study undertaken in 2021 to determine the prevalence of Salmonella spp., Escherichia coli and antimicrobial resistance (AMR) in frozen, breaded or battered chicken products on retail sale in the UK. This study sought to obtain data on AMR levels in Salmonella and E. coli in these products, in line with a number of other FSA instigated studies of the incidence and nature of AMR in the UK food chain, for example, the systematic review (2016). Between the beginning of April and the end of July 2021, 310 samples of frozen, breaded or battered chicken products containing either raw or partly cooked chicken, were collected using representative sampling of retailers in England, Wales, Scotland and Northern Ireland based on market share data. Samples included domestically produced and imported chicken products and were tested for E. coli (including extended-spectrum beta-lactamase (ESBL)-producing, colistin-resistant and carbapenem-resistant E. coli) and Salmonella spp. One isolate of each bacterial type from each contaminated sample was randomly selected for additional AMR testing to determine the minimum inhibitory concentration (MIC) for a range of antimicrobials. More detailed analysis based on Whole Genome Sequencing (WGS) data was used to further characterise Salmonella spp. isolates and allow the identification of potential links with human isolates. Salmonella spp. were detected in 5 (1.6%) of the 310 samples and identified as Salmonella Infantis (in three samples) and S. Java (in two samples). One of the S. Infantis isolates fell into the same genetic cluster as S. Infantis isolates from three recent human cases of infection; the second fell into another cluster containing two recent cases of infection. Countries of origin recorded on the packaging of the five Salmonella contaminated samples were Hungary (n=1), Ireland (n=2) and the UK (n=2). One S. Infantis isolate was multi-drug resistant (i.e. resistant to three different classes of antimicrobials), while the other Salmonella isolates were each resistant to at least one of the classes of antimicrobials tested. E. coli was detected in 113 samples (36.4%), with counts ranging from <3 to >1100 MPN (Most Probable Number)/g. Almost half of the E. coli isolates (44.5%) were susceptible to all antimicrobials tested. Multi-drug resistance was detected in 20.0% of E. coli isolates. E. coli isolates demonstrating the ESBL (but not AmpC) phenotype were detected in 15 of the 310 samples (4.8%) and the AmpC phenotype alone was detected in two of the 310 samples (0.6%) of chicken samples. Polymerase Chain Reaction (PCR) testing showed that five of the 15 (33.3%) ESBL-producing E. coli carried blaCTX-M genes (CTX-M-1, CTX-M-55 or CTX-M-15), which confer resistance to third generation cephalosporin antimicrobials. One E. coli isolate demonstrated resistance to colistin and was found to possess the mcr-1 gene. The five Salmonella-positive samples recovered from this study, and 20 similar Salmonella-positive samples from a previous UKHSA (2020/2021) study (which had been stored frozen), were subjected to the cooking procedures described on the sample product packaging for fan assisted ovens. No Salmonella were detected in any of these 25 samples after cooking. The current survey provides evidence of the presence of Salmonella in frozen, breaded and battered chicken products in the UK food chain, although at a considerably lower incidence than reported in an earlier (2020/2021) study carried out by PHE/UKHSA as part of an outbreak investigation where Salmonella prevalence was found to be 8.8%. The current survey also provides data on the prevalence of specified AMR bacteria found in the tested chicken products on retail sale in the UK. It will contribute to monitoring trends in AMR prevalence over time within the UK, support comparisons with data from other countries, and provide a baseline against which to monitor the impact of future interventions. While AMR activity was observed in some of the E. coli and Salmonella spp. examined in this study, the risk of acquiring AMR bacteria from consumption of these processed chicken products is low if the products are cooked thoroughly and handled hygienically.
APA, Harvard, Vancouver, ISO, and other styles
6

Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz, and Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, February 2001. http://dx.doi.org/10.32747/2001.7573998.bard.

Full text
Abstract:
The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
APA, Harvard, Vancouver, ISO, and other styles
7

Constatine, Aloyce, Zita Ekeocha, Stephen Robert Byrn, and Kari L. Clase. Quality of Sample Testing in the Laboratory Unit: Current Situation and Strategies for Improvement. Purdue University, December 2021. http://dx.doi.org/10.5703/1288284317446.

Full text
Abstract:
The purpose of this study was to understand the status quo of quality sample testing in the laboratory unit. A quantitative research method was used. An extensive laboratory documents (protocol, worksheets, laboratory analytical plan, standard operating procedures and manuals) review was performed and a networking approach to both management and lab staff at all levels was reviewed in order to identify all non-conformities occurred in the past three years. Results identified 36 number of results deviated from reference standards among different test performed, 400 number of samples lost, the number of laboratory personnel who were not sufficiently trained to take the task properly decreased from 16 in 2016 to 6 in 2018 after conducting training on laboratory quality management system, 36 controlled documents including sample management standard operating procedure, bench job aids were missing and 8 customer complains about the delay of results and quality laboratory of services have been identified.
APA, Harvard, Vancouver, ISO, and other styles
8

Weiss, W. Jason, Chunyu Qiao, Burkan Isgor, and Jan Olek. Implementing Rapid Durability Measure for Concrete Using Resistivity and Formation Factor. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317120.

Full text
Abstract:
The durability of in-place concrete is a high priority issue for concrete pavements and bridges. Several studies have been conducted by INDOT to use electrical resistivity as a measure of fluid transport properties. Resistivity is dependent on the chemistry of the cement and supplementary cementitious system used, as such it has been recommended that rather than specifying resistivity it may be more general to specify the formation factor. Samples were tested to establish the current levels of performance for concrete pavements in the state of Indiana. Temperature and moisture corrections are presented and acceptable accelerated aging procedure is presented. A standardized testing procedure was developed (AASHTO TP 119–Option A) resulting in part from this study that provides specific sample conditioning approaches to address pore solution composition, moisture conditioning, and testing procedures. An accelerated aging procedure is discussed to obtain later age properties (91 days) after only 28 days.
APA, Harvard, Vancouver, ISO, and other styles
9

Jorgensen, Frieda, Andre Charlett, Craig Swift, Anais Painset, and Nicolae Corcionivoschi. A survey of the levels of Campylobacter spp. contamination and prevalence of selected antimicrobial resistance determinants in fresh whole UK-produced chilled chickens at retail sale (non-major retailers). Food Standards Agency, June 2021. http://dx.doi.org/10.46756/sci.fsa.xls618.

Full text
Abstract:
Campylobacter spp. are the most common bacterial cause of foodborne illness in the UK, with chicken considered to be the most important vehicle for this organism. The UK Food Standards Agency (FSA) agreed with industry to reduce Campylobacter spp. contamination in raw chicken and issued a target to reduce the prevalence of the most contaminated chickens (those with more than 1000 cfu per g chicken neck skin) to below 10 % at the end of the slaughter process, initially by 2016. To help monitor progress, a series of UK-wide surveys were undertaken to determine the levels of Campylobacter spp. on whole UK-produced, fresh chicken at retail sale in the UK. The data obtained for the first four years was reported in FSA projects FS241044 (2014/15) and FS102121 (2015 to 2018). The FSA has indicated that the retail proxy target for the percentage of highly contaminated raw whole retail chickens should be less than 7% and while continued monitoring has demonstrated a sustained decline for chickens from major retailer stores, chicken on sale in other stores have yet to meet this target. This report presents results from testing chickens from non-major retailer stores (only) in a fifth survey year from 2018 to 2019. In line with previous practise, samples were collected from stores distributed throughout the UK (in proportion to the population size of each country). Testing was performed by two laboratories - a Public Health England (PHE) laboratory or the Agri-Food & Biosciences Institute (AFBI), Belfast. Enumeration of Campylobacter spp. was performed using the ISO 10272-2 standard enumeration method applied with a detection limit of 10 colony forming units (cfu) per gram (g) of neck skin. Antimicrobial resistance (AMR) to selected antimicrobials in accordance with those advised in the EU harmonised monitoring protocol was predicted from genome sequence data in Campylobacter jejuni and Campylobacter coli isolates The percentage (10.8%) of fresh, whole chicken at retail sale in stores of smaller chains (for example, Iceland, McColl’s, Budgens, Nisa, Costcutter, One Stop), independents and butchers (collectively referred to as non-major retailer stores in this report) in the UK that are highly contaminated (at more than 1000 cfu per g) with Campylobacter spp. has decreased since the previous survey year but is still higher than that found in samples from major retailers. 8 whole fresh raw chickens from non-major retailer stores were collected from August 2018 to July 2019 (n = 1009). Campylobacter spp. were detected in 55.8% of the chicken skin samples obtained from non-major retailer shops, and 10.8% of the samples had counts above 1000 cfu per g chicken skin. Comparison among production plant approval codes showed significant differences of the percentages of chicken samples with more than 1000 cfu per g, ranging from 0% to 28.1%. The percentage of samples with more than 1000 cfu of Campylobacter spp. per g was significantly higher in the period May, June and July than in the period November to April. The percentage of highly contaminated samples was significantly higher for samples taken from larger compared to smaller chickens. There was no statistical difference in the percentage of highly contaminated samples between those obtained from chicken reared with access to range (for example, free-range and organic birds) and those reared under standard regime (for example, no access to range) but the small sample size for organic and to a lesser extent free-range chickens, may have limited the ability to detect important differences should they exist. Campylobacter species was determined for isolates from 93.4% of the positive samples. C. jejuni was isolated from the majority (72.6%) of samples while C. coli was identified in 22.1% of samples. A combination of both species was found in 5.3% of samples. C. coli was more frequently isolated from samples obtained from chicken reared with access to range in comparison to those reared as standard birds. C. jejuni was less prevalent during the summer months of June, July and August compared to the remaining months of the year. Resistance to ciprofloxacin (fluoroquinolone), erythromycin (macrolide), tetracycline, (tetracyclines), gentamicin and streptomycin (aminoglycosides) was predicted from WGS data by the detection of known antimicrobial resistance determinants. Resistance to ciprofloxacin was detected in 185 (51.7%) isolates of C. jejuni and 49 (42.1%) isolates of C. coli; while 220 (61.1%) isolates of C. jejuni and 73 (62.9%) isolates of C. coli isolates were resistant to tetracycline. Three C. coli (2.6%) but none of the C. jejuni isolates harboured 23S mutations predicting reduced susceptibility to erythromycin. Multidrug resistance (MDR), defined as harbouring genetic determinants for resistance to at least three unrelated antimicrobial classes, was found in 10 (8.6%) C. coli isolates but not in any C. jejuni isolates. Co-resistance to ciprofloxacin and erythromycin was predicted in 1.7% of C. coli isolates. 9 Overall, the percentages of isolates with genetic AMR determinants found in this study were similar to those reported in the previous survey year (August 2016 to July 2017) where testing was based on phenotypic break-point testing. Multi-drug resistance was similar to that found in the previous survey years. It is recommended that trends in AMR in Campylobacter spp. isolates from retail chickens continue to be monitored to realise any increasing resistance of concern, particulary to erythromycin (macrolide). Considering that the percentage of fresh, whole chicken from non-major retailer stores in the UK that are highly contaminated (at more than 1000 cfu per g) with Campylobacter spp. continues to be above that in samples from major retailers more action including consideration of interventions such as improved biosecurity and slaughterhouse measures is needed to achieve better control of Campylobacter spp. for this section of the industry. The FSA has indicated that the retail proxy target for the percentage of highly contaminated retail chickens should be less than 7% and while continued monitoring has demonstrated a sustained decline for chickens from major retailer stores, chicken on sale in other stores have yet to meet this target.
APA, Harvard, Vancouver, ISO, and other styles
10

Jorgensen, Frieda, John Rodgers, Daisy Duncan, Joanna Lawes, Charles Byrne, and Craig Swift. Levels and trends of antimicrobial resistance in Campylobacter spp. from chicken in the UK. Food Standards Agency, September 2022. http://dx.doi.org/10.46756/sci.fsa.dud728.

Full text
Abstract:
Campylobacter spp. are the most common bacterial cause of foodborne illness in the UK, with chicken considered to be the most important vehicle of transmission for this organism. It is estimated there are 500,000 cases of campylobacteriosis in the UK annually, with Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) accounting for approximately 91% and 8 % of infections, respectively. Although severe infection in humans is uncommon, treatment is seldom needed for human infection but usually involves the administration of a macrolide (e.g., azithromycin) or a fluoroquinolone (e.g., ciprofloxacin). An increased rate of resistance in Campylobacter in chicken to such antimicrobials could limit effective treatment options for human infections and it is therefore important to monitor changes in rates of resistance over time. In this report we analysed trends in antimicrobial resistance (AMR) in C. jejuni and C. coli isolated from chicken in the UK. The chicken samples were from chicken reared for meat (ie. broiler chicken as opposed to layer chicken (ie. egg-laying chicken)) and included chicken sampled at slaughterhouses as well as from retail stores in the UK. Datasets included AMR results from retail surveys of Campylobacter spp. on chicken sampled in the UK from various projects in the time period from 2001 to 2020. In the retail surveys, samples were obtained from stores including major and minor retail stores throughout the UK (in proportion to the population size of each nation) and Campylobacter spp. testing was performed using standard methods with the majority of isolates obtained from direct culture on standard media (mCCDA). Data from national scale surveys of broiler chicken, sampling caecal contents and carcase neckskins at slaughterhouses, undertaken by APHA in 2007/2008, and between 2012 and 2018 were also included in the study. In the APHA-led surveys, Campylobacter were isolated using standard culture methods (culture onto mCCDA) and antimicrobial susceptibility testing was performed by a standard microbroth dilution method to determine the minimum inhibitory concentration (MIC) of isolates. Care was taken when comparing data from different studies as there had been changes to the threshold used to determine if an isolate was susceptible or resistant to an antimicrobial in a small number of scenarios. Harmonised thresholds (using epidemiological cut-off (ECOFF) values) were employed to assess AMR with appropriate adjustments made where required to allow meaningful comparisons of resistance prevalence over time. Data from additional isolates where resistance to antimicrobials were predicted from genome sequence data were also considered.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Two sample testing' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography