Articles de revues : « Weak instrument »

1

Murray, Michael P. « Avoiding Invalid Instruments and Coping with Weak Instruments ». Journal of Economic Perspectives 20, n^o 4 (1 août 2006) : 111–32. http://dx.doi.org/10.1257/jep.20.4.111.

Texte intégral

Résumé :

Archimedes said, “Give me the place to stand, and a lever long enough, and I will move the Earth.” Economists have their own powerful lever: the instrumental variable estimator. The instrumental variable estimator can avoid the bias that ordinary least squares suffers when an explanatory variable in a regression is correlated with the regression's disturbance term. But, like Archimedes' lever, instrumental variable estimation requires both a valid instrument on which to stand and an instrument that isn't too short (or “too weak”). This paper briefly reviews instrumental variable estimation, discusses classic strategies for avoiding invalid instruments (instruments themselves correlated with the regression's disturbances), and describes recently developed strategies for coping with weak instruments (instruments only weakly correlated with the offending explanator).

Styles APA, Harvard, Vancouver, ISO, etc.

2

Choi, Jaerim, Jiaying Gu et Shu Shen. « Weak-instrument robust inference for two-sample instrumental variables regression ». Journal of Applied Econometrics 33, n^o 1 (21 juin 2017) : 109–25. http://dx.doi.org/10.1002/jae.2580.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

3

Hahn, Jinyong, et Guido Kuersteiner. « Discontinuities of weak instrument limiting distributions ». Economics Letters 75, n^o 3 (mai 2002) : 325–31. http://dx.doi.org/10.1016/s0165-1765(01)00622-x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

4

Denault, William R. P., Jon Bohlin, Christian M. Page, Stephen Burgess et Astanand Jugessur. « Cross-fitted instrument : A blueprint for one-sample Mendelian randomization ». PLOS Computational Biology 18, n^o 8 (29 août 2022) : e1010268. http://dx.doi.org/10.1371/journal.pcbi.1010268.

Texte intégral

Résumé :

Bias from weak instruments may undermine the ability to estimate causal effects in instrumental variable regression (IVR). We present here a new approach to handling weak instrument bias through the application of a new type of instrumental variable coined ‘Cross-Fitted Instrument’ (CFI). CFI splits the data at random and estimates the impact of the instrument on the exposure in each partition. These estimates are then used to perform an IVR on each partition. We adapt CFI to the Mendelian randomization (MR) setting and term this adaptation ‘Cross-Fitting for Mendelian Randomization’ (CFMR). We show that, even when using weak instruments, CFMR is, at worst, biased towards the null, which makes it a conservative one-sample MR approach. In particular, CFMR remains conservative even when the two samples used to perform the MR analysis completely overlap, whereas current state-of-the-art approaches (e.g., MR RAPS) display substantial bias in this setting. Another major advantage of CFMR lies in its use of all of the available data to select genetic instruments, which maximizes statistical power, as opposed to traditional two-sample MR where only part of the data is used to select the instrument. Consequently, CFMR is able to enhance statistical power in consortia-led meta-analyses by enabling a conservative one-sample MR to be performed in each cohort prior to a meta-analysis of the results across all the cohorts. In addition, CFMR enables a cross-ethnic MR analysis by accounting for ethnic heterogeneity, which is particularly important in meta-analyses where the participating cohorts may have different ethnicities. To our knowledge, none of the current MR approaches can account for such heterogeneity. Finally, CFMR enables the application of MR to exposures that are either rare or difficult to measure, which would normally preclude their analysis in the regular two-sample MR setting.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Keele, Luke, et Jason W. Morgan. « How strong is strong enough ? Strengthening instruments through matching and weak instrument tests ». Annals of Applied Statistics 10, n^o 2 (juin 2016) : 1086–106. http://dx.doi.org/10.1214/16-aoas932.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

6

Finlay, Keith, et Leandro M. Magnusson. « Implementing Weak-Instrument Robust Tests for a General Class of Instrumental-Variables Models ». Stata Journal : Promoting communications on statistics and Stata 9, n^o 3 (septembre 2009) : 398–421. http://dx.doi.org/10.1177/1536867x0900900304.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

7

Chao, John C., Norman R. Swanson, Jerry A. Hausman, Whitney K. Newey et Tiemen Woutersen. « ASYMPTOTIC DISTRIBUTION OF JIVE IN A HETEROSKEDASTIC IV REGRESSION WITH MANY INSTRUMENTS ». Econometric Theory 28, n^o 1 (13 septembre 2011) : 42–86. http://dx.doi.org/10.1017/s0266466611000120.

Texte intégral

Résumé :

This paper derives the limiting distributions of alternative jackknife instrumental variables (JIV) estimators and gives formulas for accompanying consistent standard errors in the presence of heteroskedasticity and many instruments. The asymptotic framework includes the many instrument sequence of Bekker (1994, Econometrica 62, 657–681) and the many weak instrument sequence of Chao and Swanson (2005, Econometrica 73, 1673–1691). We show that JIV estimators are asymptotically normal and that standard errors are consistent provided that $\root \of {K_n } /r_n \to 0$ as n→∞, where Kn and rn denote, respectively, the number of instruments and the concentration parameter. This is in contrast to the asymptotic behavior of such classical instrumental variables estimators as limited information maximum likelihood, bias-corrected two-stage least squares, and two-stage least squares, all of which are inconsistent in the presence of heteroskedasticity, unless Kn/rn→0. We also show that the rate of convergence and the form of the asymptotic covariance matrix of the JIV estimators will in general depend on the strength of the instruments as measured by the relative orders of magnitude of rn and Kn.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Li, Hong, et Zhijie Xiao. « Weak instrument inference in the presence of parameter instability ». Econometrics Journal 15, n^o 3 (1 octobre 2012) : 395–419. http://dx.doi.org/10.1111/j.1368-423x.2012.00384.x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

9

Yuan, Quan, Yan Shen et Liang Chen. « Virtual Instrument for Weak Signal Detecting on Monostable Stochastic Resonance ». Advanced Materials Research 279 (juillet 2011) : 361–66. http://dx.doi.org/10.4028/www.scientific.net/amr.279.361.

Texte intégral

Résumé :

Stochastic resonance (SR) is a nonlinear phenomenon which can be used to detect weak signal. The theory of SR in a biased mono-stable system driven by multiplicative and additive white noise as well as a weak periodic signal is investigated. The virtual instrument (VI) for weak signal detecting based on this theory is designed with LabVIEW. This instrument can be used to detect weak periodic signals which meets the conditions given and can greatly improved the power spectrum of the weak signal. The results that related to different sets of parameters are given and the features of these results are in accordance with the theory of mono-stable SR. Thus, the application of this theory in the detecting of weak signal is proven to be valid.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Bazzi, Samuel, et Michael A. Clemens. « Blunt Instruments : Avoiding Common Pitfalls in Identifying the Causes of Economic Growth ». American Economic Journal : Macroeconomics 5, n^o 2 (1 avril 2013) : 152–86. http://dx.doi.org/10.1257/mac.5.2.152.

Texte intégral

Résumé :

Concern has intensified in recent years that many instrumental variables used in widely-cited growth regressions may be invalid, weak, or both. Attempts to remedy this general problem remain inadequate. We show how a range of published studies can offer more evidence that their results are not spurious. Key steps include: grounding growth regressions in more generalized theoretical models, deployment of new methods for estimating sensitivity to violations of exclusion restrictions, opening the “black box” of GMM with supportive evidence of instrument strength, and utilization of weak-instrument robust tests and estimators. (JEL C52, E23, F35, O41, O47)

Styles APA, Harvard, Vancouver, ISO, etc.

11

Chen, J., et D. S. Venables. « A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases ». Atmospheric Measurement Techniques Discussions 3, n^o 5 (27 octobre 2010) : 4571–602. http://dx.doi.org/10.5194/amtd-3-4571-2010.

Texte intégral

Résumé :

Abstract. Accurate absorption spectra of gases in the near-ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the 3B1−X1A1 transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0 × 10−46 cm5 molecule−2. We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br2 and O3.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Chen, J., et D. S. Venables. « A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases ». Atmospheric Measurement Techniques 4, n^o 3 (1 mars 2011) : 425–36. http://dx.doi.org/10.5194/amt-4-425-2011.

Texte intégral

Résumé :

Abstract. Accurate absorption spectra of gases in the near–ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the 3B1-X1A1 transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0×10−46 cm5 molecule−2. We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br2 and O3.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Adebayo, Adetunji Olumuyiwa, et Ibrahim Mohammed Nasir. « Strengthening Nigeria's Weak Institutions through the Instrument of Civic Education ». Kuwait Chapter of Arabian Journal of Business and Management Review 3, n^o 12 (août 2014) : 238–44. http://dx.doi.org/10.12816/0018827.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

14

Kripfganz, Sebastian, et Jan F. Kiviet. « kinkyreg : Instrument-free inference for linear regression models with endogenous regressors ». Stata Journal : Promoting communications on statistics and Stata 21, n^o 3 (septembre 2021) : 772–813. http://dx.doi.org/10.1177/1536867x211045575.

Texte intégral

Résumé :

In models with endogenous regressors, a standard regression approach is to exploit just-identifying or overidentifying orthogonality conditions by using instrumental variables. In just-identified models, the identifying orthogonality assumptions cannot be tested without the imposition of other nontestable assumptions. While formal testing of overidentifying restrictions is possible, its interpretation still hinges on the validity of an initial set of untestable just-identifying orthogonality conditions. We present the kinkyreg command for kinky least-squares inference, which adopts an alternative approach to identification. By exploiting nonorthogonality conditions in the form of bounds on the admissible degree of endogeneity, feasible test procedures can be constructed that do not require instrumental variables. The kinky least-squares confidence bands can be more informative than confidence intervals obtained from instrumental-variables estimation, especially when the instruments are weak. Moreover, the approach facilitates a sensitivity analysis for standard instrumental-variables inference. In particular, it allows the user to assess the validity of previously untestable just-identifying exclusion restrictions. Further instrument-free tests include linear hypotheses, functional form, heteroskedasticity, and serial correlation tests.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Kripfganz, Sebastian, et Jan F. Kiviet. « kinkyreg : Instrument-free inference for linear regression models with endogenous regressors ». Stata Journal : Promoting communications on statistics and Stata 21, n^o 3 (septembre 2021) : 772–813. http://dx.doi.org/10.1177/1536867x211045575.

Texte intégral

Résumé :

In models with endogenous regressors, a standard regression approach is to exploit just-identifying or overidentifying orthogonality conditions by using instrumental variables. In just-identified models, the identifying orthogonality assumptions cannot be tested without the imposition of other nontestable assumptions. While formal testing of overidentifying restrictions is possible, its interpretation still hinges on the validity of an initial set of untestable just-identifying orthogonality conditions. We present the kinkyreg command for kinky least-squares inference, which adopts an alternative approach to identification. By exploiting nonorthogonality conditions in the form of bounds on the admissible degree of endogeneity, feasible test procedures can be constructed that do not require instrumental variables. The kinky least-squares confidence bands can be more informative than confidence intervals obtained from instrumental-variables estimation, especially when the instruments are weak. Moreover, the approach facilitates a sensitivity analysis for standard instrumental-variables inference. In particular, it allows the user to assess the validity of previously untestable just-identifying exclusion restrictions. Further instrument-free tests include linear hypotheses, functional form, heteroskedasticity, and serial correlation tests.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Bertie, John E., R. Norman Jones, Yoram Apelblat et C. Dale Keefe. « Infrared Intensities of Liquids XIII : Accurate Optical Constants and Molar Absorption Coefficients between 6500 and 435 cm−1 of Toluene at 25°C, from Spectra Recorded in Several Laboratories ». Applied Spectroscopy 48, n^o 1 (janvier 1994) : 127–43. http://dx.doi.org/10.1366/0003702944027516.

Texte intégral

Résumé :

This paper presents accurate infrared absorption intensities of liquid toluene at 25°C. The accuracy is estimated from the agreement between the intensities measured by different spectroscopists using the same instrument in the same laboratory and also by different spectroscopists in different laboratories using instruments made by different manufacturers. The average agreement between integrated intensities over specific wavenumber ranges is about ±1.8%. The spectra from the different laboratories have been averaged, unweighted, to give intensity spectra of toluene that are presented as the best available. The use of data from different instruments in different laboratories has included the influence of systematic instrumental errors, so that the precision of the intensity data presented should be a better approximation to its accuracy than would be the case from an extensive study by one person on one instrument. The results obtained agree with the only measurements that have been made against a primary standard, the estimated accuracy of which is about 6%. The results are presented as graphs and tables of the molar absorption coefficient spectrum and the real and imaginary refractive index spectra between 6500 and 435 cm−1. The peak heights and the areas under the bands in the imaginary refractive index (i.e., absorption index) and molar absorption coefficient spectra are reported. The absorption index, k(ν˜), and molar absorption coefficient, Em (ν˜), values are believed to be accurate to an average ±2.5% at the peaks of 39 strong, medium, and weak bands and ±1.9% at the peaks of 51 very weak bands below 4100 cm−1. Above 4100 cm−1, 11 very weak bands have an average accuracy of ±1.3%. The baseline k(ν˜) values are accurate to between ±3 and ±10%. The areas under bands or band groups in k(ν˜) and εm (ν˜) spectra are accurate to 2.4% on average, or 1.2% for strong, medium, and weak band groups between 3150 and 775 cm−1 with 0.002 < kmax < 0.112. The real refractive index, n(ν˜), values are believed to be accurate to 0.2%.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Wara, Michael. « Instrument Choice, Carbon Emissions, and Information ». Michigan Journal of Environmental & ; Administrative Law, n^o 4.2 (2015) : 261. http://dx.doi.org/10.36640/mjeal.4.2.instrument.

Texte intégral

Résumé :

This Article examines the consequences of a previously unrecognized difference between pollutant cap-and-trade schemes and pollution taxes. Implementation of cap-and-trade relies on a forecast of future emissions, while implementation of a pollution tax does not. Realistic policy designs using either regulatory instrument almost always involve a phase-in over time to avoid economic disruption. Cap-and-trade accomplishes this phase-in via a limit on emissions that falls gradually below the forecast of future pollutant emissions. Emissions taxation accomplishes the same via a gradually increasing levy on pollution. Because of the administrative complexity of establishing an emissions trading market, cap-and-trade programs typically require between three and five years lead time before imposing obligations on emitters. In this Article, I present new evidence showing that forecast error over this timeframe for United States energy- related carbon dioxide emissions from the Department of Energy’s energy model—the model used for policy design by Congress and EPA—is biased and imprecise to such a degree as to make its use impractical. The forecasted emissions are insufficiently accurate to allow for creation of a reliable or predictable market signal to incentivize emission reductions. By contrast, carbon taxes, because they do not depend upon a baseline emissions forecast, create a relatively clear level of policy stringency. This difference matters because policies that end up weaker than intended face low odds for strengthening, while those that end up stronger than intended are likely to be weakened. The political asymmetry combined with actual model forecast errors leads to bias in favor of suboptimal, weak, policies for cap-and-trade. This is a serious concern if, as is usually the case, a cap is set based on political bargaining rather than on an optimal balancing of abatement costs and avoided climate damage. By contrast, the same model bias would lead to more environmentally effective than forecast carbon taxes but without the political consequences created by price volatility, were such programs to be implemented in the United States. Thus, while theory tells us that cap-and-trade and carbon taxes can be equivalent, imperfect information leads to suboptimal environmental performance of emissions trading, relative to carbon taxation policies. Policymakers should weigh these practical, information-related concerns when considering approaches to controlling emissions of greenhouse gases.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Hadiati, Soka, Anita Anita et Adi Pramuda. « Pengembangan Instrumen Penilaian Afektif Pada Asisten Praktikum Laboratorium Fisika ». Radiasi : Jurnal Berkala Pendidikan Fisika 13, n^o 2 (2 octobre 2020) : 35–39. http://dx.doi.org/10.37729/radiasi.v13i2.263.

Texte intégral

Résumé :

This study aims to develop affective assessment instruments for practical assistants in physics laboratories. The development model used Plomp development model, consisting of five stages, namely: (1) the initial investigation stage; (2) Design; (3) Realization / construction stage; (4) testing, evaluation and revision; (5) implementation. The questionnaire is prepared based on theory and proven by its relevance (content validation) by experts. Collecting data in this study using non-test data collection techniques in the form of affective / attitude questionnaires. The affective score obtained will be analyzed the validity of the instrument construct using the analysis rash model theory with the winsteps program. Reliability using Alpha Cronbach. The attitude instrument was designed with reference to the criteria and indicators based on Rao's theory. Content validity by 7 experts showed that all items had good validity. The inter rater reliability of the questions was 0.8. Empirical validity shows that all items are valid. The instrument has item reliability 0.93 and person reliability 0.39 with good and moderate categories. This shows that the consistency of the answers from the subject is still weak, but the quality of the items in the instrument's reliability aspect is quite good. The instrument that has been developed meets the criteria of validity and reliability.

Styles APA, Harvard, Vancouver, ISO, etc.

19

Palmer, Tom M., Debbie A. Lawlor, Roger M. Harbord, Nuala A. Sheehan, Jon H. Tobias, Nicholas J. Timpson, George Davey Smith et Jonathan AC Sterne. « Using multiple genetic variants as instrumental variables for modifiable risk factors ». Statistical Methods in Medical Research 21, n^o 3 (7 janvier 2011) : 223–42. http://dx.doi.org/10.1177/0962280210394459.

Texte intégral

Résumé :

Mendelian randomisation analyses use genetic variants as instrumental variables (IVs) to estimate causal effects of modifiable risk factors on disease outcomes. Genetic variants typically explain a small proportion of the variability in risk factors; hence Mendelian randomisation analyses can require large sample sizes. However, an increasing number of genetic variants have been found to be robustly associated with disease-related outcomes in genome-wide association studies. Use of multiple instruments can improve the precision of IV estimates, and also permit examination of underlying IV assumptions. We discuss the use of multiple genetic variants in Mendelian randomisation analyses with continuous outcome variables where all relationships are assumed to be linear. We describe possible violations of IV assumptions, and how multiple instrument analyses can be used to identify them. We present an example using four adiposity-associated genetic variants as IVs for the causal effect of fat mass on bone density, using data on 5509 children enrolled in the ALSPAC birth cohort study. We also use simulation studies to examine the effect of different sets of IVs on precision and bias. When each instrument independently explains variability in the risk factor, use of multiple instruments increases the precision of IV estimates. However, inclusion of weak instruments could increase finite sample bias. Missing data on multiple genetic variants can diminish the available sample size, compared with single instrument analyses. In simulations with additive genotype-risk factor effects, IV estimates using a weighted allele score had similar properties to estimates using multiple instruments. Under the correct conditions, multiple instrument analyses are a promising approach for Mendelian randomisation studies. Further research is required into multiple imputation methods to address missing data issues in IV estimation.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Liu, Xuanchao, et Wenlong Ni. « Weak Signal Detection with Duffing Oscillator Based on Virtual Instrument Technology ». International Journal of Online Engineering (iJOE) 11, n^o 1 (25 janvier 2015) : 20. http://dx.doi.org/10.3991/ijoe.v11i1.4114.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

21

Yasin, Ayman, Mahmoud Al Qudah et Helen Al-Gweiri. « The Phonological Alternations in the Noun of Instrument (fɪʕɑ:l) ». International Journal of Linguistics 8, n^o 1 (24 février 2016) : 51. http://dx.doi.org/10.5296/ijl.v8i1.9094.

Texte intégral

Résumé :

The present paper aims at examining Arabic phonological alternations that occur when deriving the noun of instrument with the pattern fɪʕɑ:l from strong and weak trilateral verbs. To this end, the researcher chose 32 nouns of instrument from Al-muʕjam al-wasi:T (2001) that represent the strong and weak trilateral verbs evenly. The findings of the present study show that the nouns of instrument which are derived from strong trilateral verbs undergo systematic alternations since the non-high vowel /ɑ/ after the first radical alternates to the high vowel /ɪ/ and the short vowel after the second radical /ɑ/ corresponds to the long vowel /ɑ:/. Nouns of instruments which are derived from weak trilateral verbs can be classified into three classes: class one undergoes a systematic alternation where the non-high vowel /ɑ/ becomes a high vowel /ɪ/ and the short vowel /ɑ/ corresponds to the long vowel /ɑ:/. As for weak verbs, the following phonological processes are motivated: change of the non-high vowel /ɑ/ to a high vowel /ɪ/, ɑ-Assimilation Rule, Lengthening, and Insertion of the glottal stop /Ɂ/ at the end of the noun of instrument preceded by a long vowel /ɑ:/. Finally, the third class has two phonological changes: the high back rounded sonorant /w/ alternates to the high front unrounded sonorant /j/. After that, the short vowel /ɑ/ is lengthened.

Styles APA, Harvard, Vancouver, ISO, etc.

22

de Haan, Victor-O., Jeroen Plomp, Wim G. Bouwman, Martin Trinker, M. Theo Rekveldt, Chris P. Duif, Erwin Jericha, Helmut Rauch et Ad A. van Well. « Phase-object approximation in small-angle neutron scattering experiments on silicon gratings ». Journal of Applied Crystallography 40, n^o 1 (12 janvier 2007) : 151–57. http://dx.doi.org/10.1107/s0021889806047558.

Texte intégral

Résumé :

The phase-object approximation for neutron scattering based on a one-dimensional dynamic forward scattering theory is discussed and used to calculate the differential cross section of an object. It is shown that this approximation is valid in ultra-small-angle neutron scattering (USANS) and spin-echo small-angle neutron scattering (SESANS) experiments on silicon gratings. In the weak scattering limit, the phase-object approximation reduces to the kinematic or first Born approximation. The spatial coherence function is used to describe instrumental resolution effects. Measurements on three different instruments are in good agreement with calculation results. In the experiment with a time-of-flight SESANS instrument, the effect ofPendellösungwith object size is observed.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Sun, Xia, Xiang You Wang, Shu Yuan Du et Ying Zhu. « A Weak Current Detection Circuit Design of Organophosphorous Pesticides Rapid Detection Portable Instrument ». Advanced Materials Research 403-408 (novembre 2011) : 2569–72. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.2569.

Texte intégral

Résumé :

In this paper, a weak current detection circuit is designed for developing organophosphorous pesticides rapid detection portable instrument. The detection principle is based on the electrochemical characteristic of enzyme catalyzing substrate of acetylcholinesterase biosensor for detecting pesticide residues. Based on the behavior of cyclic voltammograms (CV) of the acetylcholinesterase biosensor, the data acquisition and processing circuit of the weak current signals generated by the biosensor is designed, which including the I/V conversion, differential amplification , low-pass filter, A/D conversion etc. Eventually, the 0~5V voltage signal are obtained and they are proportional to the weak current from the enzyme biosensor. The designed detection circuit has a good consistence compared with electrochemical analysis instrument, which can establish a good base for developing organophosphorous pesticides rapid detection portable instrument.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Chevillon, Guillaume, Sophocles Mavroeidis et Zhaoguo Zhan. « ROBUST INFERENCE IN STRUCTURAL VECTOR AUTOREGRESSIONS WITH LONG-RUN RESTRICTIONS ». Econometric Theory 36, n^o 1 (5 mars 2019) : 86–121. http://dx.doi.org/10.1017/s0266466619000045.

Texte intégral

Résumé :

Long-run restrictions are a very popular method for identifying structural vector autoregressions, but they suffer from weak identification when the data is very persistent, i.e., when the highest autoregressive roots are near unity. Near unit roots introduce additional nuisance parameters and make standard weak-instrument-robust methods of inference inapplicable. We develop a method of inference that is robust to both weak identification and strong persistence. The method is based on a combination of the Anderson-Rubin test with instruments derived by filtering potentially nonstationary variables to make them near stationary using the IVX instrumentation method of Magdalinos and Phillips (2009). We apply our method to obtain robust confidence bands on impulse responses in two leading applications in the literature.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Yudha, Kiki Devista, et Jagar Lumbantoruan. « HUBUNGAN HASIL BELAJAR TEORI MUSIK DASAR DAN PRAKTEK INSTRUMEN PERKUSI DI JURUSAN SENDRATASIK ». Jurnal Sendratasik 9, n^o 3 (3 septembre 2020) : 37. http://dx.doi.org/10.24036/jsu.v9i1.109303.

Texte intégral

Résumé :

Abstract This study aims at finding out the correlation between learning outcomes in music theory subject and percussion instrument practice subject in the Department of Drama, Dnace and Music Arts. This quantitative research used a correlational method involving two variables, i.e. the learning outcomes of music theory subject and the learning outcomes percussion instrument practice subject. The population in this study was the students of Department of Drama, Dance and Music Arts, Faculty of Languages and Arts, Universitas Negeri Padang whi took Music Theory subject in the even semester of 2017-18 academic calendar. Meanwhile, the sample in this study was the students of the Department of Drama, Dance and Music Arts who took the Percussion Instrument Practice subject in the even semester of 2018-19 academic calendar. The data of this study were documentation of the students’ learning outcomes in music theory and percussion instrument practice subjects which were processed using the Pearson product moment correlation test method. The results of data analysis showed that the value of the correlation test was 0.1013 or 10.13%. This coefficient value was based on the interpretation of the coefficient values in the range 0.00 – 0.19, indicating that the level of correlation between music theory subject and percussion instrument subject was very weak. Using a significance test with an error level of 5%, the results of the hypothesis testing showed that rcount ˂ rtable, indicating that Ha was accepted and Ho was rejected. This means that there is a correlation between the learning outcomes of music theory subject in its application to the practice of percussion instrument, but in a very weak level.Keywords: relationships, learning outcomes, basic music theory, percussion instruments

Styles APA, Harvard, Vancouver, ISO, etc.

26

Tian, Tian, Zhen Yu Li, Tian Gao, Fang Yao Liu et Jian Wu. « Weak Signal Detection and Application in Electronic Experiment Based on Virtual Instrument ». Applied Mechanics and Materials 511-512 (février 2014) : 294–300. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.294.

Texte intégral

Résumé :

Base on the virtual instrument technology, a micro signal measurement system was established and applied to the electronic teaching experiment. It is composed of PC, oscilloscope, signal generator, ac constant current source, low noise preamplifier and tested operational amplifier, etc. it can complete the measurement of uV weak voltage, uA weak current measure, wires and printing plate conductor resistance and inductance, amplifier open-loop amplitude frequency and phase frequency characteristics, and so on many aspects of modern electronic measurement experiment content. The system not only has the characteristics of functional diversity, measurement accuracy, and good graphic interface, simple operation and overcomes the shortcomings in the course of electronic technology experiment teaching, and play an important role on improving the experimental conditions,reducing the cost of experiments, raising the level of classroom teaching and practice of teaching.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Kleibergen, Frank, et Sophocles Mavroeidis. « Weak Instrument Robust Tests in GMM and the New Keynesian Phillips Curve ». Journal of Business & ; Economic Statistics 27, n^o 3 (juillet 2009) : 293–311. http://dx.doi.org/10.1198/jbes.2009.08280.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

Perron, Benoit. « Semiparametric Weak-Instrument Regressions with an Application to the Risk-Return Tradeoff ». Review of Economics and Statistics 85, n^o 2 (mai 2003) : 424–43. http://dx.doi.org/10.1162/003465303765299918.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

29

Huntington-Klein, Nick. « Instruments with Heterogeneous Effects : Bias, Monotonicity, and Localness ». Journal of Causal Inference 8, n^o 1 (19 décembre 2020) : 182–208. http://dx.doi.org/10.1515/jci-2020-0011.

Texte intégral

Résumé :

AbstractIn Instrumental Variables (IV) estimation, the effect of an instrument on an endogenous variable may vary across the sample. In this case, IV produces a local average treatment effect (LATE), and if monotonicity does not hold, then no effect of interest is identified. In this paper, I calculate the weighted average of treatment effects that is identified under general first-stage effect heterogeneity, which is generally not the average treatment effect among those affected by the instrument. I then describe a simple set of data-driven approaches to modeling variation in the effect of the instrument. These approaches identify a Super-Local Average Treatment Effect (SLATE) that weights treatment effects by the corresponding instrument effect more heavily than LATE. Even when first-stage heterogeneity is poorly modeled, these approaches considerably reduce the impact of small-sample bias compared to standard IV and unbiased weak-instrument IV methods, and can also make results more robust to violations of monotonicity. In application to a published study with a strong instrument, the preferred approach reduces error by about 19% in small (N ≈ 1, 000) subsamples, and by about 13% in larger (N ≈ 33, 000) subsamples.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Chao, John C. « PANEL STRUCTURAL MODELING WITH WEAK INSTRUMENTATION AND COVARIANCE RESTRICTIONS ». Econometric Theory 30, n^o 4 (23 avril 2014) : 839–81. http://dx.doi.org/10.1017/s0266466613000492.

Texte intégral

Résumé :

This paper considers estimating a panel data simultaneous equations model under both coefficient and covariance matrix restrictions in a scenario where one or the other set of identifying restrictions may be invalid or may hold only weakly. We study the limiting properties of various estimators in an asymptotic framework, which takes both the cross-sectional dimensionNand the time dimensionTto infinity. In this setting as in the pure cross-sectional setup, the performance of the 2SLS estimator depends on the strength of the identifying conditions imposed on the coefficients of the model, and it fails to be consistent once these conditions break down sufficiently resulting in instruments that are too weakly correlated with the endogenous regressors. On the other hand, the between-group (BG) estimator is consistent and asymptotically normal even when coefficient restrictions fail, but it has the shortcoming that its precision depends only on variations in the cross-sectional dimension; and, hence, it is less efficient and has slower rate of convergence than alternatives, which make better use of the large time dimension. A GMM estimator, which combines the moment conditions of theBGestimator with that of the within-group IV estimator, is more robust to instrument weakness than 2SLS and is more efficient than theBGestimator, but it has a second-order bias even under strong instruments if the assumed covariance restrictions do not hold. To remedy the deficiency of the aforementioned estimators, we propose in this paper two new model averaging estimators, which are weighted averages of the GMM estimator and a bias-corrected GMM estimator. The two proposed estimators have weighting functions that depend on alternative transformations of the Bayesian Information Criterion (BIC), which is employed here to assess the validity of the covariance restrictions. We show that these new estimators have some nice robustness properties against possible failure of either the coefficient restrictions or the covariance restrictions.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Assyifaa, Ghina Aghnia Nur, Eis Nurzakiyah, Lilik Hasanah et Hera Novia. « Rasch Analysis of Creative Thinking Skill on Optical Instrument (CTSOI) 11th Grade Students Sundanese Tribe : a Case Study ». Radiasi : Jurnal Berkala Pendidikan Fisika 14, n^o 1 (30 avril 2021) : 51–61. http://dx.doi.org/10.37729/radiasi.v14i1.1080.

Texte intégral

Résumé :

This study aims to determine the creative thinking skills at optic instruments of Sundanese tribe, 11th-grade students. This research is a case study research conducted at a high school in Majalengka district, West Java. Totaling 32 students consisting of 12 male students, namely “Aa”, 20 female students, namely “Teteh”, and 18 Sundanese, the rest are immigrants. The instrument used is the Test for Creative Thinking-optical instrument (TCT-OI) which has existed validated by experts. The data found were investigated with Rasch Analysis Model (RAM). Based on the results of the analysis using the Rasch Analysis, it was found that the creative thinking ability of students stayed static low can be shown by the value of Person reliability which is 0.21 included in the weak category. There are variances in the level of creative thinking skills of students from the Sundanese and non-Sundanese tribes. As a result, it is necessary to develop creative thinking skill on the optical instrument, 11th grade students Sundanese tribe

Styles APA, Harvard, Vancouver, ISO, etc.

32

Fu, Jun, Yujia Xu et Yumeng Shi. « Development and Application of Non-Destructive Testing Instrument for Wall Impermeability Based on a Water Drenching Method ». Symmetry 14, n^o 5 (11 mai 2022) : 987. http://dx.doi.org/10.3390/sym14050987.

Texte intégral

Résumé :

This article introduces a new type of on-site non-destructive testing instrument for the impermeability measurement of walls. The research and development of this instrument is based on the water drenching method. The influence of symmetry is mainly considered in the design process, and it has on-site testing functions such as water pressure adjustment and wind pressure simulation. The water seepage of the four types of masonry walls under the combined working conditions of three levels of spray strength and wind pressure strength was tested by using instruments. The results show that the weak location regarding the impermeability of the masonry wall is the junction of mortar joints. Parameters such as wall leakage time, seepage area and water seepage amount are significantly affected by wind pressure. Furthermore, during on-site inspection, the influence of wind pressure on water seepage conditions must be considered when simulating the real wind-driven rain conditions. The testing instrument will be promoted and used according to the compiled industry regulations.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Qin, Gang, Han Li et Xiao Gang Feng. « The Design of Portable Electromyograph and Induced Instrument ». Advanced Materials Research 482-484 (février 2012) : 439–43. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.439.

Texte intégral

Résumé :

Aiming at the complex operation , low performance-to-price ratio and the weak adaptability of the like products at present, this paper designs one type of portable electromyograph and induced instrument, The detector uses S3C2440, low power consumption but high performance ,as its main processor. it designs sEMG signal detection module by itself, and proceed electromyography collection, display and storage in time. The practical use shows that the instrument is chiefly featured by complete functions, low power consumption, simple portable, low price, and extensive application etc.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Imbens, Guido W., et Paul R. Rosenbaum. « Robust, accurate confidence intervals with a weak instrument : quarter of birth and education ». Journal of the Royal Statistical Society : Series A (Statistics in Society) 168, n^o 1 (janvier 2005) : 109–26. http://dx.doi.org/10.1111/j.1467-985x.2004.00339.x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Sanderson, Eleanor, et Frank Windmeijer. « A weak instrument F-test in linear IV models with multiple endogenous variables ». Journal of Econometrics 190, n^o 2 (février 2016) : 212–21. http://dx.doi.org/10.1016/j.jeconom.2015.06.004.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

36

Pratumvinit, Busadee, Leslie Lam, Narisorn Kongruttanachok, Chinnawut Hemthong, Gerald J. Kost, Panumas Kamkang et Kanit Reesukumal. « Anion gap reference intervals show instrument dependence and weak correlation with albumin levels ». Clinica Chimica Acta 500 (janvier 2020) : 172–79. http://dx.doi.org/10.1016/j.cca.2019.10.012.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

37

Bull, Craig L., Michael W. Johnson, Hayrullo Hamidov, Kazuki Komatsu, Malcolm Guthrie, Matthias J. Gutmann, John S. Loveday et Richard J. Nelmes. « An improved method for calibrating time-of-flight Laue single-crystal neutron diffractometers ». Journal of Applied Crystallography 47, n^o 3 (29 mai 2014) : 974–83. http://dx.doi.org/10.1107/s1600576714006657.

Texte intégral

Résumé :

A robust and comprehensive method for determining the orientation matrix of a single-crystal sample using the neutron Laue time-of-flight (TOF) technique is described. The new method enables the measurement of the unit-cell parameters with an uncertainty in the range 0.015–0.06%, depending upon the crystal symmetry and the number of reflections measured. The improved technique also facilitates the location and integration of weak reflections, which are often more difficult to discern amongst the increased background at higher energies. The technique uses a mathematical model of the relative positions of all the detector pixels of the instrument, together with a methodology that establishes a reproducible reference frame and a method for determining the parameters of the instrument detector model. Since all neutron TOF instruments require precise detector calibration for their effective use, it is possible that the method described here may be of use on other instruments where the detector calibration cannot be determined by other means.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Liao, Xiu Ying, Hui Cheng et Yi Cheng Bai. « Design and Application of Natural Audio Electric Field Frequency Selecting Instrument ». Applied Mechanics and Materials 103 (septembre 2011) : 15–19. http://dx.doi.org/10.4028/www.scientific.net/amm.103.15.

Texte intégral

Résumé :

An observation scheme, which is designed several frequencies suited over the natural audio electric field frequency range, is used to qualitatively understand the electrical structure of underground geological body. Weak signal detection technology has been used to amplify and filter the weak natural electric field signal, and read out them after selecting corresponding frequencies and integrating. This instrument can observe eight natural electric field signal at frequency of 8Hz, 16Hz, 32Hz, 64Hz, 128Hz, 256Hz, 512Hz, 1024Hz. Several reliable technologies have been used in the hardware design and software development to improve both the anti-interferences capability and system stability. Compared with field work instance, we conclude that natural audio electric field frequency selecting instrument can get the underground geological information within a certain depth, and therefore it can be used for fast survey in geology and mineral resources, and in engineering geophysical and water resources.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Fadhel, Ibrahim Eskandar Ibrahim, Syed Zulkarnain Bin Syed Idrus, Mohd Syukri Yeoh Abdullah, Amani Ali Elmetwaly Ali Ibrahim et Mazni Binti Omar. « Systems success measurement : instrument & ; framework a new perspective ». Independent Journal of Management & ; Production 10, n^o 5 (1 octobre 2019) : 1572. http://dx.doi.org/10.14807/ijmp.v10i5.872.

Texte intégral

Résumé :

There are major concerns regarding the previous research that can be said as having poor measurements, lack of theoretical grounding, and concern heavily on investment justifies. Some are also considered as having weak survey instruments, inappropriate data collection approaches, and lack of agreement on the dependent variables measurement that resulted in its incompatibility. Several related issues pertaining to high rates of systems’ failure that justify the heavy investment costs and affect the systems’ success of measurement. This matter had raised a high concern, especially for the researchers, practitioners, organization managers and systems administrators. Thus, the successful measurement of any systems is vital. The purpose of this study is to provide a framework and a high-quality validated instrument based on the literature review and experts’ validation. Subsequently, it can be used in the future studies to efficiently assist in the systems’ success measurement. The statistical test of 344 users with the smart PLS for the instrument shows an excellent result.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Supianto, Supianto, Kumaidi Kumaidi et Yoyon Suryono. « Development of project-based historical knowledge assessment instruments ». Historical Encounters : A journal of historical consciousness, historical cultures, and history education 8, n^o 1 (2021) : 16–29. http://dx.doi.org/10.52289/hej8.102.

Texte intégral

Résumé :

The history teacher is quite often using a project-based learning model to improve students' historical knowledge and skills. Unfortunately, this learning model is not supported by the availability of qualified assessment instruments. The limitations of project assessment instruments make teachers rely more on subjectivity in assessing student projects. Meanwhile, to assess historical knowledge, most teachers still use multiple choice and essay questions. Both types of assessments provide little information about students' abilities and are not sufficient as a basis for teachers to make decisions in the classroom. Therefore, it is necessary to develop an assessment instrument that can be used in assessing students' knowledge based on the project that they produce in project-based learning. This study aims to develop a project-based historical knowledge assessment instrument that has good evidence of validity and reliability that can be used to measure students' historical knowledge more precisely and more accurately. Historical knowledge is assessed based on six indicators: what, who, where, when, why, and how. The six indicators are described in a 12 item Likert scale. Based on these 12 items, students' historical knowledge was classified into four categories: very high, high, acceptable, and weak. The instrument was tested on 426 10th grade high school students in Yogyakarta, Indonesia. The test results data were used to analyze the characteristics of the instrument consisting of validity and reliability. The test results show that the instrument developed is valid and reliable, so it is suitable to be used to assess historical knowledge on a broader scale.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Bright, Frank V., et Gary M. Hieftje. « A New Technique for the Elimination of Fluorescence Interference in Raman Spectroscopy ». Applied Spectroscopy 40, n^o 5 (juillet 1986) : 583–87. http://dx.doi.org/10.1366/0003702864508511.

Texte intégral

Résumé :

A new instrument for Raman spectroscopy has been constructed with the use of a cw or mode-locked argon-ion laser as the excitation source and a microwave spectrum analyzer for discrimination between fluorescence and Raman scatter. To demonstrate the new instrument's capability, the weak Raman scatter of water was resolved from the intense fluorescence from rhodamine 6G. Theoretically predicted relative errors in the new procedure are calculated and experimental results are shown to be in good agreement with theory.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Choi, Byeong Yeob. « Instrumental variable estimation of truncated local average treatment effects ». PLOS ONE 16, n^o 4 (5 avril 2021) : e0249642. http://dx.doi.org/10.1371/journal.pone.0249642.

Texte intégral

Résumé :

Instrumental variable (IV) analysis is used to address unmeasured confounding when comparing two nonrandomized treatment groups. The local average treatment effect (LATE) is a causal estimand that can be identified by an IV. The LATE approach is appealing because its identification relies on weaker assumptions than those in other IV approaches requiring a homogeneous treatment effect assumption. If the instrument is confounded by some covariates, then one can use a weighting estimator, for which the outcome and treatment are weighted by instrumental propensity scores. The weighting estimator for the LATE has a large variance when the IV is weak and the target population, i.e., the compliers, is relatively small. We propose a truncated LATE that can be estimated more reliably than the regular LATE in the presence of a weak IV. In our approach, subjects who contribute substantially to the weak IV are identified by their probabilities of being compliers, and they are removed based on a pre-specified threshold. We discuss interpretation of the proposed estimand and related inference method. Simulation and real data experiments demonstrate that the proposed truncated LATE can be estimated more precisely than the standard LATE.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Lutfia Fajriah, Endang Surahman et Romy Faisal Mustofa. « Relationship Between Critical Thinking Skills and Students' Decision-Making Skills on Virus Materials In MAN 1 Tasikmalaya ». Mangifera Edu 6, n^o 1 (9 octobre 2021) : 68–81. http://dx.doi.org/10.31943/mangiferaedu.v6i1.115.

Texte intégral

Résumé :

This research aims to find out the relationship between critical thinking skills and students' decision-making skills on viral material in MAN 1 Tasikmalaya Regency. The research method used is correlational. The population in this study was all students of class X MIPA consisting of 8 classes. The sampling technique uses purposive sampling with samples class X MIPA 3, X MIPA 4, and X MIPA 5 with 107 students. Data collection techniques using instruments in the form of tests. The research instrument used in this study consists of two instruments, namely critical thinking skills instruments in the form of a question in the form of a description, as many as ten questions with five indicators. For the instrument of decision-making skills in the form of a question in the form of a description, as many as 12 questions with five indicators. The data analysis technique used is a bivariate correlation test. Based on the results of research shows that critical thinking skills have a weak relationship with decision-making skills. This is evidenced by a correlation coefficient value of 0.208 with a determination coefficient value of 4.3%. Keywords: Critical Thinking Skills, Decision Making Skills, Virus Material.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Cherenkov, A. D. « Theoretical Analysis of Instrument Transducers for Monitoring the Extremely Weak Luminescence of Biological Objects ». Telecommunications and Radio Engineering 52, n^o 2 (1998) : 69–72. http://dx.doi.org/10.1615/telecomradeng.v52.i2.150.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

45

Bun, Maurice J. G., et Frank Windmeijer. « The weak instrument problem of the system GMM estimator in dynamic panel data models ». Econometrics Journal 13, n^o 1 (1 février 2010) : 95–126. http://dx.doi.org/10.1111/j.1368-423x.2009.00299.x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

46

Wu, Ang, Juan Hua Zhu et Xiao Ning Hu. « Design and Implement of a Food Safety Testing Instrument Based on Microcontroller ». Key Engineering Materials 480-481 (juin 2011) : 1201–5. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.1201.

Texte intégral

Résumé :

A food safety testing instrument is designed and developed based microcontroller. The instrument includes optical unit, conditioning unit and control and acquisition unit. The optical unit converts the chemiluminescence signals into electrical signals through photoelectric sensor. Conditioning circuit mainly amplifies the weak signal to an appropriate range. Control and data acquisition circuit consists of the MCU, LCD and memory circuit. The experiment shows that the correlation coefficient (R2) between the phosphate ion concentration and emitting area was 0.98. The instrument is small，cheap and reliable. It shows that the instrument can successfully used to quick measurement for food safety in field.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Supriadi, Supriadi, Wildan Wildan, Aliefman Hakim, Jeckson Siahaan, Mukhtar Haris et Sunniarti Ariani. « Mental model and scientific reasoning ability of chemistry education students during Covid-19 Pandemic online learning ». Jurnal Pijar Mipa 17, n^o 3 (31 mai 2022) : 400–406. http://dx.doi.org/10.29303/jpm.v17i3.3106.

Texte intégral

Résumé :

This study aims to find: (1) the development of students' scientific reasoning abilities; (2) mental models developed by students in understanding the concept of dissolving weak acids and weak bases; and (3) the relationship between scientific reasoning abilities and mental models. The research approach is a descriptive study. The research subjects were 38 first-year students of the Chemical Education Study Program, Faculty of Teacher Training and Education, The University of Mataram. The research data collected were scientific reasoning ability data and student mental model data on the concept of dissolving weak acids and weak bases. Students' scientific reasoning ability was measured using the revised Classroom Test of Scientific Reasoning (CTSR) instrument in 2000, developed by Lawson and translated into Indonesian. The translation test has a reliability coefficient, calculated by the KR-20 formula, of 0.74. Identification of mental models using written tests and interviews. The content validity of the mental model test instruments is 94.2%. The data obtained were analyzed descriptively. The identification of mental models is made by using a constant comparative technique. The results showed a delay in developing students' scientific reasoning abilities compared to the criteria set by Lawson. Most of the students developed initial mental models in understanding dissolving weak acids and bases. In addition, the higher the student's scientific reasoning ability, the mental model developed tends to approach the scientific mental model.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Van Humbeeck, G., Ch Van Audenhove, G. Storms, M. De Hert, G. Pieters, H. Vertommen, J. Peuskens et J. Heyrman. « Expressed Emotion in the Client-Professional Dyad ». European Journal of Psychological Assessment 20, n^o 4 (janvier 2004) : 237–46. http://dx.doi.org/10.1027/1015-5759.20.4.237.

Texte intégral

Résumé :

Summary: Background: This article reports on a study of the concurrent validity between the standard expressed emotion instrument, the Camberwell Family Interview (CFI), and two alternative EE measures, the Level of Expressed Emotion (LEE) and the Perceived Criticism Scale (PCS). Methods: The research sample consisted of 56 schizophrenic clients, who were residing in sheltered residences, and 56 professionals. Results: Based on the results of the correlation matrix between all the subscales of the instruments, a significantly positive relationship was found between the criticism scale of the CFI, the total score of the LEE, and the client version of the PCS. These correlations, however, were rather weak, which implies that the three instruments have little in common with each other. The professionals' version of the PCS does not appear to be an EE instrument. Conclusions: The results suggest that the CFI still remains the best instrument for assessing EE in a therapeutic relationship (between a professional and a client). If there is insufficient time to administer the CFI, then the client version of the PCS and the LEE can be used with the qualification that the PCS and LEE also measure other aspects and thus cannot completely replace the CFI. Nevertheless, the research indicates that asking the clients would seem to provide a better indication of the level of the professionals' criticism rather than asking the professionals themselves directly.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Lu, Qi Rong, Yan Bing Wei, Bing Huang et Dong Mei Gao. « A Method of Lower S/N Signal Detection by Amplifier and Computer ». Advanced Materials Research 433-440 (janvier 2012) : 4559–64. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.4559.

Texte intégral

Résumé :

A new detection method of weak signal mixed in strong noise is proposed. The method includes theory scheme, hardware and software. It detects and processes signal by using the instrument magnifying technology and single-chip microcomputer control. By means of virtual instrumentation simulation and display, this design provides effective methods to detect µA-level weak signal in piezoelectric infrared detector. Through the experiment of simulate low frequency weak signal detection, the system fully reveals its practicality and superiority in the field of lower S/N signal detection.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Patonov, Nikolay. « Fiscal Impacts on Output in a Small Open Economy : The Case of Albania ». Scientific Annals of Economics and Business 63, n^o 2 (2016) : 161–69. http://dx.doi.org/10.1515/saeb-2016-0113.

Texte intégral

Résumé :

The paper is intended to study the effects of total government spending and tax revenue on the annual GDP growth rate in Albania. On this base, we can examine whether and to which extent the macroeconomic governance could rely on those fiscal instruments in terms of a small open economy. The empirical methodology is based on regression analysis which includes OLS estimation on simply specified regression model and Vector Autoregressive estimates. The results support the assumptions that government expenditure is a weak instrument for policy impacts and the government must rely on taxation to stimulate economic growth.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Weak instrument »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres