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Tests and confidence sets with correct size when instruments are potentially weak AgEcon
Mikusheva, Anna; Poi, Brian P..
We consider inference in the linear regression model with one endogenous variable and potentially weak instruments. We construct confidence sets for the coefficient on the endogenous variable by inverting the Anderson–Rubin, Lagrange multiplier, and conditional likelihood-ratio tests. Our confidence sets have correct coverage probabilities even when the instruments are weak. We propose a numerically simple algorithm for finding these confidence sets, and we present a Stata command that supersedes the one presented in Moreira and Poi (Stata Journal 3: 57–70).
Tipo: Journal Article Palavras-chave: Condivreg; Instrumental variables; Weak instruments; Confidence set; Similar test; Research Methods/ Statistical Methods.
Ano: 2006 URL: http://purl.umn.edu/117584
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From the help desk: Demand system estimation AgEcon
Poi, Brian P..
This article provides an example illustrating how to use Stata to estimate systems of household demand equations. More generally, the techniques developed here can be used to estimate any system of nonlinear equations using Stata’s maximum likelihood routines.
Tipo: Journal Article Palavras-chave: Nonlinear estimation; Maximum likelihood; Demand equations; Research Methods/ Statistical Methods.
Ano: 2002 URL: http://purl.umn.edu/116025
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From the help desk: Swamy's random-coefficients model AgEcon
Poi, Brian P..
This article discusses the Swamy (1970) random-coefficients model and presents a command that extends Stata’s xtrchh command by also providing estimates of the panel-specific coefficients.
Tipo: Journal Article Palavras-chave: Panel data; Random-coefficients models; Research Methods/ Statistical Methods.
Ano: 2003 URL: http://purl.umn.edu/116121
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Stata tip 58: nl is not just for nonlinear models AgEcon
Poi, Brian P..
Tipo: Article Palavras-chave: Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/120938
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Jackknife instrumental variables estimation in Stata AgEcon
Poi, Brian P..
The two-stage least-squares (2SLS) instrumental variables estimator is commonly used to address endogeneity. However, the estimator suffers from bias that is exacerbated when the instruments are only weakly correlated with the endogenous variables and when many instruments are used. In this article, I discuss jackknife instrumental variables estimation as an alternative to 2SLS. Monte Carlo simulations comparing the jackknife instrument variables estimators to 2SLS and limited information maximum likelihood (LIML) show that two of the four variants perform remarkably well even when 2SLS does not. In a weak-instrument experiment, the two best performing jackknife estimators also outperform LIML.
Tipo: Journal Article Palavras-chave: Jive; 2SLS; LIML; JIVE; Instrumental variables; Endogeneity; Weak instruments; Research Methods/ Statistical Methods.
Ano: 2006 URL: http://purl.umn.edu/117586
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Production function estimation in Stata using inputs to control for unobservables AgEcon
Petrin, Amil; Poi, Brian P.; Levinsohn, James.
A key issue in the estimation of production functions is the correlation between unobservable productivity shocks and input levels. Profit-maximizing firms respond to positive productivity shocks by expanding output, which requires additional inputs. Negative shocks lead firms to pare back output, decreasing their input usage. Olley and Pakes (1996) develop an estimator that uses investment as a proxy for these unobservable shocks. More recently, Levinsohn and Petrin (2003a) introduce an estimator that uses intermediate inputs as proxies, arguing that intermediates may respond more smoothly to productivity shocks. This paper reviews Levinsohn and Petrin’s approach and introduces a Stata command that implements it.
Tipo: Journal Article Palavras-chave: Levpet; Production functions; Productivity; Endogeneity; GMM estimator; Research Methods/ Statistical Methods.
Ano: 2004 URL: http://purl.umn.edu/116231
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Implementing tests with correct size in the simultaneous equations model AgEcon
Moreira, Marcelo J.; Poi, Brian P..
In this paper, we propose a fix to the size distortions of tests for structural parameters in the simultaneous equations model by computing critical value functions based on the conditional distribution of test statistics. The conditional tests can then be used to construct informative confidence regions for the structural parameter with correct coverage probability. Commands to implement these tests in Stata are also introduced.
Tipo: Journal Article Palavras-chave: Instrumental variables; Weak instruments; Similar tests; Score test; Wald test; Likelihood-ratio test; Confidence regions; 2SLS estimator; LIML estimator; Research Methods/ Statistical Methods.
Ano: 2002 URL: http://purl.umn.edu/116032
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Demand–system estimation: Update AgEcon
Poi, Brian P..
The nlsur command is better suited to demand-system estimation than the suite of ado-files provided in Poi (2002, Stata Journal 2: 403–410) because it is faster and requires only one ancillary ado-file. This article replicates the results presented in Poi (2002) by using nlsur instead of ml.
Tipo: Article Palavras-chave: Nlsur; Demand-system estimation; Nonlinear estimation; Maximum likelihood; Demand equations; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/122621
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Production function estimation in Stata using the Olley and Pakes method AgEcon
Yasar, Mahmut; Raciborski, Rafal; Poi, Brian P..
Productivity is often computed by approximating the weighted sum of the inputs from the estimation of the Cobb–Douglas production function. Such estimates, however, may suffer from simultaneity and selection biases. Olley and Pakes (1996, Econometrica 64: 1263–1297) introduced a semiparametric method that allows us to estimate the production function parameters consistently and thus obtain reliable productivity measures by controlling for such biases. This study first reviews this method and then introduces a Stata command to implement it. We show that when simultaneity and selection biases are not controlled for, the coefficients for the variable inputs are biased upward and the coefficients for the fixed inputs are biased downward.
Tipo: Article Palavras-chave: Opreg; Levpet; Production function; Bias; Simultaneity; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/122587
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From the help desk: Some bootstrapping techniques AgEcon
Poi, Brian P..
Bootstrapping techniques have become increasingly popular in applied econometrics and other areas. This article presents several methods and shows how to implement them using Stata’s bootstrap command.
Tipo: Journal Article Palavras-chave: Bssize initial; Bssize refine; Bssize analyze; Bssize cleanup; Bootstrap; Confidence intervals; Percentile-t; Dependent processes; Research Methods/ Statistical Methods.
Ano: 2004 URL: http://purl.umn.edu/116251
Registros recuperados: 10
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