Download or read book Higher order Optimal Estimation of Binary Average Treatment Effects written by Paul Joseph Gift and published by . This book was released on 2002 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Efficient Estimation of Average Treatment Effects Using the Estimated Propensity Score written by Keisuke Hirano and published by . This book was released on 2000 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are interested in estimating the average effect of a binary treatment on a scalar outcome. If assignment to the treatment is independent of the potential outcomes given pretreatment variables, biases associated with simple treatment-control average comparisons can be removed by adjusting for differences in the pre-treatment variables. Rosenbaum and Rubin (1983, 1984) show that adjusting solely for differences between treated and control units in a scalar function of the pre-treatment, the propensity score, also removes the entire bias associated with differences in pre-treatment variables. Thus it is possible to obtain unbiased estimates of the treatment effect without conditioning on a possibly high-dimensional vector of pre-treatment variables. Although adjusting for the propensity score removes all the bias, this can come at the expense of efficiency. We show that weighting with the inverse of a nonparametric estimate of the propensity score, rather than the true propensity score, leads to efficient estimates of the various average treatment effects. This result holds whether the pre-treatment variables have discrete or continuous distributions. We provide intuition for this result in a number of ways. First we show that with discrete covariates, exact adjustment for the estimated propensity score is identical to adjustment for the pre-treatment variables. Second, we show that weighting by the inverse of the estimated propensity score can be interpreted as an empirical likelihood estimator that efficiently incorporates the information about the propensity score. Finally, we make a connection to results to other results on efficient estimation through weighting in the context of variable probability sampling.

Download or read book Estimation of Dose response Functions and Optimal Treatment Doses with a Continuous Treatment written by Carlos Arturo Flores Villela and published by . This book was released on 2005 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009-07 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the Second Seattle Symposium in Biostatistics written by Danyu Lin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains a selection of papers presented at the Second Seattle Symposium in Biostatistics: Analysis of Correlated Data. The symposium was held in 2000 to celebrate the 30th anniversary of the University of Washington School of Public Health and Community Medicine. It featured keynote lectures by Norman Breslow, David Cox and Ross Prentice and 16 invited presentations by other prominent researchers. The papers contained in this volume encompass recent methodological advances in several important areas, such as longitudinal data, multivariate failure time data and genetic data, as well as innovative applications of the existing theory and methods. This volume is a valuable reference for researchers and practitioners in the field of correlated data analysis.

Download or read book Targeted Learning written by Mark J. van der Laan and published by Springer Science & Business Media. This book was released on 2011-06-17 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: The statistics profession is at a unique point in history. The need for valid statistical tools is greater than ever; data sets are massive, often measuring hundreds of thousands of measurements for a single subject. The field is ready to move towards clear objective benchmarks under which tools can be evaluated. Targeted learning allows (1) the full generalization and utilization of cross-validation as an estimator selection tool so that the subjective choices made by humans are now made by the machine, and (2) targeting the fitting of the probability distribution of the data toward the target parameter representing the scientific question of interest. This book is aimed at both statisticians and applied researchers interested in causal inference and general effect estimation for observational and experimental data. Part I is an accessible introduction to super learning and the targeted maximum likelihood estimator, including related concepts necessary to understand and apply these methods. Parts II-IX handle complex data structures and topics applied researchers will immediately recognize from their own research, including time-to-event outcomes, direct and indirect effects, positivity violations, case-control studies, censored data, longitudinal data, and genomic studies.

Download or read book Targeted Learning in Data Science written by Mark J. van der Laan and published by Springer. This book was released on 2018-03-28 with total page 655 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook for graduate students in statistics, data science, and public health deals with the practical challenges that come with big, complex, and dynamic data. It presents a scientific roadmap to translate real-world data science applications into formal statistical estimation problems by using the general template of targeted maximum likelihood estimators. These targeted machine learning algorithms estimate quantities of interest while still providing valid inference. Targeted learning methods within data science area critical component for solving scientific problems in the modern age. The techniques can answer complex questions including optimal rules for assigning treatment based on longitudinal data with time-dependent confounding, as well as other estimands in dependent data structures, such as networks. Included in Targeted Learning in Data Science are demonstrations with soft ware packages and real data sets that present a case that targeted learning is crucial for the next generation of statisticians and data scientists. Th is book is a sequel to the first textbook on machine learning for causal inference, Targeted Learning, published in 2011. Mark van der Laan, PhD, is Jiann-Ping Hsu/Karl E. Peace Professor of Biostatistics and Statistics at UC Berkeley. His research interests include statistical methods in genomics, survival analysis, censored data, machine learning, semiparametric models, causal inference, and targeted learning. Dr. van der Laan received the 2004 Mortimer Spiegelman Award, the 2005 Van Dantzig Award, the 2005 COPSS Snedecor Award, the 2005 COPSS Presidential Award, and has graduated over 40 PhD students in biostatistics and statistics. Sherri Rose, PhD, is Associate Professor of Health Care Policy (Biostatistics) at Harvard Medical School. Her work is centered on developing and integrating innovative statistical approaches to advance human health. Dr. Rose’s methodological research focuses on nonparametric machine learning for causal inference and prediction. She co-leads the Health Policy Data Science Lab and currently serves as an associate editor for the Journal of the American Statistical Association and Biostatistics.

Download or read book Moving the Goalposts written by and published by . This book was released on 2006 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estimation of average treatment effects under unconfoundedness or exogenous treatment assignment is often hampered by lack of overlap in the covariate distributions. This lack of overlap can lead to imprecise estimates and can make commonly used estimators sensitive to the choice of specification. In such cases researchers have often used informal methods for trimming the sample. In this paper we develop a systematic approach to addressing such lack of overlap. We characterize optimal subsamples for which the average treatment effect can be estimated most precisely, as well as optimally weighted average treatment effects. Under some conditions the optimal selection rules depend solely on the propensity score. For a wide range of distributions a good approximation to the optimal rule is provided by the simple selection rule to drop all units with estimated propensity scores outside the range [0.1,0.9]

Download or read book Analysis of Repeated Measures written by Martin J. Crowder and published by Routledge. This book was released on 2017-10-24 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Repeated measures data arise when the same characteristic is measured on each case or subject at several times or under several conditions. There is a multitude of techniques available for analysing such data and in the past this has led to some confusion. This book describes the whole spectrum of approaches, beginning with very simple and crude methods, working through intermediate techniques commonly used by consultant statisticians, and concluding with more recent and advanced methods. Those covered include multiple testing, response feature analysis, univariate analysis of variance approaches, multivariate analysis of variance approaches, regression models, two-stage line models, approaches to categorical data and techniques for analysing crossover designs. The theory is illustrated with examples, using real data brought to the authors during their work as statistical consultants.

Download or read book Estimation of Treatment Effects with High dimensional Controls written by Alexandre Belloni and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We propose methods for inference on the average effect of a treatment on a scalar outcome in the presence of very many controls. Our setting is a partially linear regression model containing the treatment/policy variable and a large number p of controls or series terms, with p that is possibly much larger than the sample size n, but where only s “n unknown controls or series terms are needed to approximate the regression function accurately. The latter sparsity condition makes it possible to estimate the entire regression function as well as the average treatment effect by selecting an approximately the right set of controls using Lasso and related methods. We develop estimation and inference methods for the average treatment effect in this setting, proposing a novel "post double selection" method that provides attractive inferential and estimation properties. In our analysis, in order to cover realistic applications, we expressly allow for imperfect selection of the controls and account for the impact of selection errors on estimation and inference. In order to cover typical applications in economics, we employ the selection methods designed to deal with non-Gaussian and heteroscedastic disturbances. We illustrate the use of new methods with numerical simulations and an application to the effect of abortion on crime rates. -- treatment effects ; high-dimensional regression ; inference under imperfect model selection

Download or read book Nonparametric IV Estimation of Local Average Treatment Effects with Covariates written by Markus Frölich and published by . This book was released on 2002 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aspects of Identification and Partial Identification of Average Treatment Effect in Binary Outcome Models written by Chuhui Li and published by . This book was released on 2015 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Average treatment effect (ATE) is a measure that is frequently used in empirical analysis for measuring the impact of a policy amendable treatment on an outcome variable. Identification and estimation of the ATE have been of concern in empirical studies, as individuals are often only observed for one of the two treatment states in non-experimental data and the selection of treatment is often endogenous. This thesis studies the identification and estimation of the ATE of a binary treatment variable on a binary outcome variable. It particularly focuses on the implication of recent theoretical developments in the literature of partial identification to the econometric estimation of policy relevant effects in empirical applications.The notion of partial identification relates to the idea that in certain situations such as limited observability, more than one data generating process (DGP), or model, can give rise to the same data set we observe; these models are said to be observationally equivalent. In such circumstances policy relevant measures such as the ATE can not be point identified. It is only possible to set identify the measure by estimating an identified set (or bound) for such measures where all values in the set are consistent with the data.The analysis in the thesis is divided to three parts. The first part assumes that data is generated from a particular DGP with an additive error and a parametric distribution. It is found that the bias in the ATE estimator arising from a mis-specified error distribution is not significantly large if we have reasonable sample size and IV strength, even though there may be more significant biases for the model coefficients estimators. We also show that under this regime, the ATE can still be estimated reasonably well even without the existence of instrumental variables (IVs), relying on the assumed functional form and sample size for identification. The main part of the analysis is carried out in the remaining chapters under the partial identification framework. Performances of the estimated ATE bounds from four different estimation methods are compared by using the Hausdorff distance and Euclidean distance. It is found that for all sample sizes in the simulation, the easy to implement parametric methods yield better estimates than nonparametric methods. The strength of IVs also plays an important role on the partial identification of the ATE. The width of the identified set drops as the instrument strength grows. If an extremely strong instrumental variable is available, we may be able to achieve point identification of the ATE (the upper bound and lower bound will overlap). The simulation results further confirms that estimators from parametric methods are robust with regard to instrument strength, while the nonparametric estimators will deviate significantly from the true when the instrument strength is relatively small. Finally the point identification and partial identification of the ATE are applied to a real world data set to study the impact of the private health insurance status on dental service utilisation in Australia.The analysis in the thesis shows that conventional empirical analysis assuming a bivariate probit model could be misleading by estimating a much smaller range for the policy effect. This thesis illustrates with practical applications how various bound analysis of the ATE can be carried out and can provide more robust estimates for policy effects under much broader assumptions for the DGP.

Download or read book Journal of Economic Literature written by and published by . This book was released on 2003 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Treatment Regimes written by Anastasios A. Tsiatis and published by CRC Press. This book was released on 2019-12-19 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic Treatment Regimes: Statistical Methods for Precision Medicine provides a comprehensive introduction to statistical methodology for the evaluation and discovery of dynamic treatment regimes from data. Researchers and graduate students in statistics, data science, and related quantitative disciplines with a background in probability and statistical inference and popular statistical modeling techniques will be prepared for further study of this rapidly evolving field. A dynamic treatment regime is a set of sequential decision rules, each corresponding to a key decision point in a disease or disorder process, where each rule takes as input patient information and returns the treatment option he or she should receive. Thus, a treatment regime formalizes how a clinician synthesizes patient information and selects treatments in practice. Treatment regimes are of obvious relevance to precision medicine, which involves tailoring treatment selection to patient characteristics in an evidence-based way. Of critical importance to precision medicine is estimation of an optimal treatment regime, one that, if used to select treatments for the patient population, would lead to the most beneficial outcome on average. Key methods for estimation of an optimal treatment regime from data are motivated and described in detail. A dedicated companion website presents full accounts of application of the methods using a comprehensive R package developed by the authors. The authors’ website www.dtr-book.com includes updates, corrections, new papers, and links to useful websites.

Download or read book Estimating Average Treatment Effects With Propensity Scores Estimated With Four Machine Learning Procedures written by Kip Brown and published by . This book was released on 2018 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background: The increased availability of claims data allows one to build high dimensional datasets, rich in covariates, for accurately estimating treatment effects in medical and epidemiological cohort studies. This paper shows the full potential of machine learning for the estimation of average treatment effects with propensity score methods in a context rich and high dimensional datasets. Methods: Four different methods are used to estimate average treatment effects in the context of time to event outcomes. The four methods explored in this study are LASSO, Random Forest, Gradient Descent Boosting and Artificial Neural networks. Simulations based on an actual medical claims data set are used to assess the efficiency of these methods. The simulations are performed with over 100, 000 observations and 1,100 explanatory variables. Each method is tested on 500 datasets that are created from the original dataset, allowing us to report the mean and standard deviation of estimated average treatment effects. Results: The results are very promising for all four methods; however, LASSO, Random Forest and Gradient Boosting seem to be performing better than Random Forest. Conclusion: Machine Learning methods can be helpful for observational studies that use the propensity score when a very large number of covariates are available, the total number of observations is large, and the dependent event rare. This is an important result given the availability of big data related to Health Economics and Outcomes Research (HEOR) around the world.

Download or read book Evaluating Optimal Individualized Treatment Rules written by Alexander Ryan Luedtke and published by . This book was released on 2016 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suppose we observe baseline covariates, a binary indicator of treatment, and an outcome occuring after treatment. An individualized treatment rule (ITR) is a treatment rule which assigns treatments to individuals based on their measured covariates. An optimal ITR is the ITR which maximizes the population mean outcome. The mean outcome of the optimal ITR is referred to as the optimal value. This dissertation considers three inferential challenges related to these parameters in the large semiparametric model that at most places restrictions on the probability of receiving treatment given covariates. The first is to develop confidence intervals for the optimal value. Constructing valid confidence intervals for this quantity is surprisingly difficult when the stratum specific treatment effect, also called the blip function, is null with positive probability. This null treatment effect seems possible in many studies. While it has been claimed in the literature that no regular and asymptotically linear (RAL) estimator exists in this case, we prove that RAL estimators of the optimal value can exist in a slightly more general setting. We then describe an approach to obtain root-n rate confidence intervals for the optimal value even when regular estimation is not possible. We also provide sufficient conditions under which our estimator is RAL and asymptotically efficient -- a necessary condition is of course that regular estimation is possible under the data generating distribution. We have thus far assumed that treatment is an unlimited resource so that the entire population can be treated if this strategy maximizes the population mean outcome. In the second part of this dissertation, we consider optimal ITRs in settings where the treatment resource is limited so that there is a maximum proportion of the population that can be treated. We give a general closed-form expression for an optimal stochastic ITR in this resource-limited setting, and a closed-form expression for the optimal deterministic ITR under an additional assumption. We also present an estimator of the mean outcome under the optimal stochastic ITR and give conditions under which our estimator is efficient among all RAL estimators. Both of the first two inferential challenges considered give parametric-rate confidence intervals for finite-dimensional parameters in our large semiparametric model. In the third part of this dissertation we focus on developing hypothesis tests and confidence sets for infinite-dimensional parameters that one typically estimates using data adaptive techniques. Parametric-rate inference is not typically expected in this setting. Our primary motivating example concerns the blip function, which is closely related to the optimal ITRs in both the resource-unconstrained and constrained settings. For any fixed function, we give valid hypothesis tests that the blip function is equal to this fixed function. These tests can then be inverted to develop a confidence set for the blip function. Surprisingly, the hypothesis test achieves a parametric rate in the sense that it is consistent against local alternatives converging to the data generating distribution at the rate of one divided by the square root of sample size. We prove the validity of this procedure in great generality that applies far beyond this particular inference problem, and reference several other examples to which it applies. The results in this third component of the dissertation have been developed using the theory of higher-order influence functions.

Download or read book Matched Sampling for Causal Effects written by Donald B. Rubin and published by Cambridge University Press. This book was released on 2006-09-04 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched sampling is often used to help assess the causal effect of some exposure or intervention, typically when randomized experiments are not available or cannot be conducted. This book presents a selection of Donald B. Rubin's research articles on matched sampling, from the early 1970s, when the author was one of the major researchers involved in establishing the field, to recent contributions to this now extremely active area. The articles include fundamental theoretical studies that have become classics, important extensions, and real applications that range from breast cancer treatments to tobacco litigation to studies of criminal tendencies. They are organized into seven parts, each with an introduction by the author that provides historical and personal context and discusses the relevance of the work today. A concluding essay offers advice to investigators designing observational studies. The book provides an accessible introduction to the study of matched sampling and will be an indispensable reference for students and researchers.