Download or read book Characterizing Selection Bias written by and published by . This book was released on 1998 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterizing Selection Bias Using Experimental Data written by and published by . This book was released on 1998 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This paper develops and applies semiparametric econometric methods to estimate the form of selection bias that arises from using nonexperimental comparison groups to evaluate social programs and to test the identifying assumptions that justify three widely-used classes of estimators and our extensions of them: (a) the method of matching; (b) the classical econometric selection model which represents the bias solely as a function of the probability of participation; and (c) the method of difference-in-differences. Using data from an experiment on a prototypical social program combined with unusually rich data from a nonexperimental comparison group, we reject the assumptions justifying matching and our extensions of that method but find evidence in support of the index-sufficient selection bias model and the assumptions that justify application of a conditional semiparametric version of the method of difference-in-difference. Fa comparable people and to appropriately weight participants and nonparticipants a sources of selection bias as conveniently measured. We present a rigorous defin bias and find that in our data it is a small component of conventially meausred it is still substantial when compared with experimentally-estimated program impa matching participants to comparison group members in the same labor market, givi same questionnaire, and making sure they have comparable characteristics substan the performance of any econometric program evaluation estimator. We show how t analysis to estimate the impact of treatment on the treated using ordinary obser.
Download or read book Sample Selection Bias as a Specification Error written by James J. Heckman and published by . This book was released on 1977 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, I present a simple characterization of the sample selection bias problem that is also applicable to the conceptually distinct econometric problems that arise from truncated samples and from models with limited dependent variables. The problem of sample selection bias is fit within the conventional specification error framework of Griliches and Theil. A simple estimator is discussed that enables analysts to utilize ordinary regression methods to estimate models free of selection bias. The techniques discussed here are applied to re-estimate and test a model of female labor supply developed by the author. (1974). This paper is in three parts. In the first section, selection bias is presented within the specification error framework. In this section, general distributional assumptions are maintained. In section two, specific results are presented for the case of normal regression disturbances. Simple estimators are proposed and discussed. In the third section, empirical results are presented
Download or read book Conditioning on the Probability of Selection to Control Selection Bias written by Joshua David Angrist and published by . This book was released on 1995 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Continuous Multivariate Distributions Volume 1 written by Samuel Kotz and published by John Wiley & Sons. This book was released on 2004-04-05 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuous Multivariate Distributions, Volume 1, Second Edition provides a remarkably comprehensive, self-contained resource for this critical statistical area. It covers all significant advances that have occurred in the field over the past quarter century in the theory, methodology, inferential procedures, computational and simulational aspects, and applications of continuous multivariate distributions. In-depth coverage includes MV systems of distributions, MV normal, MV exponential, MV extreme value, MV beta, MV gamma, MV logistic, MV Liouville, and MV Pareto distributions, as well as MV natural exponential families, which have grown immensely since the 1970s. Each distribution is presented in its own chapter along with descriptions of real-world applications gleaned from the current literature on continuous multivariate distributions and their applications.
Download or read book Character Selection Bias Using Experimental Data written by James Joseph Heckman and published by . This book was released on 1998 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Developing a Protocol for Observational Comparative Effectiveness Research A User s Guide written by Agency for Health Care Research and Quality (U.S.) and published by Government Printing Office. This book was released on 2013-02-21 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This User’s Guide is a resource for investigators and stakeholders who develop and review observational comparative effectiveness research protocols. It explains how to (1) identify key considerations and best practices for research design; (2) build a protocol based on these standards and best practices; and (3) judge the adequacy and completeness of a protocol. Eleven chapters cover all aspects of research design, including: developing study objectives, defining and refining study questions, addressing the heterogeneity of treatment effect, characterizing exposure, selecting a comparator, defining and measuring outcomes, and identifying optimal data sources. Checklists of guidance and key considerations for protocols are provided at the end of each chapter. The User’s Guide was created by researchers affiliated with AHRQ’s Effective Health Care Program, particularly those who participated in AHRQ’s DEcIDE (Developing Evidence to Inform Decisions About Effectiveness) program. Chapters were subject to multiple internal and external independent reviews. More more information, please consult the Agency website: www.effectivehealthcare.ahrq.gov)
Download or read book Selection Bias in Evaluating Treatment Effects written by Arthur Stanley Goldberger and published by . This book was released on 1972 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reviews and Self selection Bias with Operational Implications written by Ningyuan Chen and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews for products and services written by previous consumers have become an influential input to the purchase decision of customers. Many service businesses monitor the reviews closely, for feedback as well as detecting service flaws, and they have become part of the performance review for service managers, with rewards tied to improvement in the aggregate rating. Many empirical papers have documented a bias in the aggregate ratings, arising due to customers' inherent self-selection in their choices and bounded rationality in evaluating previous reviews. While there is a vast empirical literature analyzing reviews, theoretical models that try to isolate and explain the bias in ratings are relatively few. Assuming consumers simply substitute the average rating they see as a proxy for quality, we give a precise characterization of the self-selection bias on ratings of an assortment of products, when consumers confound ex-ante innate preferences for a product or service with ex-post experience and service quality and do not separate the two. We develop a parsimonious choice model for consumer purchase decisions and show that the mechanism leads to an upward bias, which is more pronounced for niche products. Based on our theoretical characterization, we study the effect on pricing and assortment decisions of the firm, when potential customers purchase based on the biased ratings. Our results give insights into how quality, prices and customer feedback are intricately tied together for service firms.
Download or read book Selection Bias Adjustment in Treatment effect Models as a Method of Aggregation written by Robert A. Moffitt and published by . This book was released on 1995 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this note is to interpret estimation of the conventional treatment-effect selection-bias model in econometrics as a method of aggregation and to draw the implications of this interpretation. In addition, the paper notes the connection of this interpretation with an older style of analysis using grouped data and illustrates the aggregation analogy with examples from the literature. The estimation technique used to illustrate the points is the method of instrumental variables.
Download or read book Applying Quantitative Bias Analysis to Epidemiologic Data written by Timothy L. Lash and published by Springer Science & Business Media. This book was released on 2011-04-14 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bias analysis quantifies the influence of systematic error on an epidemiology study’s estimate of association. The fundamental methods of bias analysis in epi- miology have been well described for decades, yet are seldom applied in published presentations of epidemiologic research. More recent advances in bias analysis, such as probabilistic bias analysis, appear even more rarely. We suspect that there are both supply-side and demand-side explanations for the scarcity of bias analysis. On the demand side, journal reviewers and editors seldom request that authors address systematic error aside from listing them as limitations of their particular study. This listing is often accompanied by explanations for why the limitations should not pose much concern. On the supply side, methods for bias analysis receive little attention in most epidemiology curriculums, are often scattered throughout textbooks or absent from them altogether, and cannot be implemented easily using standard statistical computing software. Our objective in this text is to reduce these supply-side barriers, with the hope that demand for quantitative bias analysis will follow.
Download or read book Studies of Selection Bias in Applied Statistic written by Gunnar Eklund and published by . This book was released on 1959 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Role of Evidence in Risk Characterization written by Peter M. Wiedemann and published by John Wiley & Sons. This book was released on 2008-09-08 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the few books to focus on the critical problem of the correct characterization of conflicting data for an adequate risk evaluation, this title comprehensively covers the different approaches in various research areas in the US and in Europe, while also considering the ethical implications of risk evaluation. In addition, special attention is paid to the sensitive topic of potential health risks through electromagnetic fields. Written by leading experts in the field, this is an indispensable resource for policy makers and professionals in health risk assessment.
Download or read book Methods for Detecting and Correcting for Selection Bias written by Patrick T. Bradshaw and published by . This book was released on 2001 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selection Bias written by Alice Orcutt Nakamura and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When a regression model is estimated using a censored subset of observations, coefficient estimates may be biased. Censored regression models have a long history in biometrics, engineering and other areas of applied statistics. The interest of economists in these models was stimulated by Tobin's work on durable goods consumption in the late 1950s. It was Heckman's publication of a simple two-step procedure for estimating censored regression models, however, that led to their widespread usage in applied econometric studies. Although this is not necessarily the best method for estimating all censored regression models, it has certain attractive properties. An understanding of this method is vital to the proper interpretation of the wealth of applied studies based on this approach. Also, valuable insights into the basic nature of sample selection problems can be gained from the formulation of the censored regression model popularized by Heckman. We begin by exploring the estimation problems resulting from censoring and from certain properties of Heckman's two-step estimation method. Procedures are developed for assessing the nature and extent of problems resulting from censoring; these procedures are then applied in an empirical analysis of the wage rates and hours of work of individuals in 10 different demographic groups using data from the Panel Study of Income Dynamics. One of our findings is that estimation using censored data can lead to bias and other related problems even when the degree of censoring is slight.
Download or read book Selection Bias in the Estimation of Experimental and Quasi experimental Effects written by Robert A. Moffitt and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selection Bias in Quasi experimental Research written by Marieke Dingena Spreeuwenberg and published by . This book was released on 2010 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt:
