arXiv subjects

Matthew R. Williams

Publications and source records attributed to Matthew R. Williams.

22 records · Page 2Linked to original sources

arXiv2019

Bayesian Uncertainty Estimation Under Complex Sampling

Social and economic studies are often implemented as complex survey designs. For example, multistage, unequal probability sampling designs utilized by federal statistical agencies are typically constructed to maximize the efficiency of the target domain level estimator (e.g., indexed by geographic area) within cost constraints for survey administration. Such designs may induce dependence between the sampled units; for example, with employment of a sampling step that selects geographically-indexed clusters of units. A sampling-weighted pseudo-posterior distribution may be used to estimate the population model on the observed sample. The dependence induced between co-clustered units inflates the scale of the resulting pseudo-posterior covariance matrix that has been shown to induce under coverage of the credibility sets. By bridging results across Bayesian model mispecification and survey sampling, we demonstrate that the scale and shape of the asymptotic distributions are different between each of the pseudo-MLE, the pseudo-posterior and the MLE under simple random sampling. Through insights from survey sampling variance estimation and recent advances in computational methods, we devise a correction applied as a simple and fast post-processing step to MCMC draws of the pseudo-posterior distribution. This adjustment projects the pseudo-posterior covariance matrix such that the nominal coverage is approximately achieved. We make an application to the National Survey on Drug Use and Health as a motivating example and we demonstrate the efficacy of our scale and shape projection procedure on synthetic data on several common archetypes of survey designs.

stat.ME↗

arXiv2019

Optimization of Survey Weights under a Large Number of Conflicting Constraints

In the analysis of survey data, sampling weights are needed for consistent estimation of the population. However, the original inverse probability weights from the survey sample design are typically modified to account for non-response, to increase efficiency by incorporating auxiliary population information, and to reduce the variability in estimates due to extreme weights. It is often the case that no single set of weights can be found which successfully incorporates all of these modifications because together they induce a large number of constraints and restrictions on the feasible solution space. For example, a unique combination of categorical variables may not be present in the sample data, even if the corresponding population level information is available. Additional requirements for weights to fall within specified ranges may also lead to fewer population level adjustments being incorporated. We present a framework and accompanying computational methods to address this issue of constraint achievement or selection within a restricted space that will produce revised weights with reasonable properties. By combining concepts from generalized raking, ridge and lasso regression, benchmarking of small area estimates, augmentation of state-space equations, path algorithms, and data-cloning, this framework simultaneously selects constraints and provides diagnostics suggesting why a fully constrained solution is not possible. Combinatoric operations such as brute force evaluations of all possible combinations of constraints and restrictions are avoided. We demonstrate this framework by applying alternative methods to post-stratification for the National Survey on Drug Use and Health. We also discuss strategies for scaling up to even larger data sets. Computations were performed in R and code is available from the authors.

stat.CO↗

arXiv2018

Bayesian Estimation Under Informative Sampling with Unattenuated Dependence

An informative sampling design leads to unit inclusion probabilities that are correlated with the response variable of interest. However, multistage sampling designs may also induce higher order dependencies, which are typically ignored in the literature when establishing consistency of estimators for survey data under a condition requiring asymptotic independence among the unit inclusion probabilities. We refine and relax this condition of asymptotic independence or asymptotic factorization and demonstrate that consistency is still achieved in the presence of residual sampling dependence. A popular approach for conducting inference on a population based on a survey sample is the use of a pseudo-posterior, which uses sampling weights based on first order inclusion probabilities to exponentiate the likelihood. We show that the pseudo-posterior is consistent not only for survey designs which have asymptotic factorization, but also for designs with residual or unattenuated dependence. Using the complex sampling design of the National Survey on Drug Use and Health, we explore the impact of multistage designs and order based sampling. The use of the survey-weighted pseudo-posterior together with our relaxed requirements for the survey design establish a broad class of analysis models that can be applied to a wide variety of survey data sets.

stat.ME↗

arXiv2017

Bayesian Pairwise Estimation Under Dependent Informative Sampling

An informative sampling design leads to the selection of units whose inclusion probabilities are correlated with the response variable of interest. Model inference performed on the resulting observed sample will be biased for the population generative model. One approach that produces asymptotically unbiased inference employs marginal inclusion probabilities to form sampling weights used to exponentiate each likelihood contribution of a pseudo likelihood used to form a pseudo posterior distribution. Conditions for posterior consistency restrict applicable sampling designs to those under which pairwise inclusion dependencies asymptotically limit to 0. There are many sampling designs excluded by this restriction; for example, a multi-stage design that samples individuals within households. Viewing each household as a population, the dependence among individuals does not attenuate. We propose a more targeted approach in this paper for inference focused on pairs of individuals or sampled units; for example, the substance use of one spouse in a shared household, conditioned on the substance use of the other spouse. We formulate the pseudo likelihood with weights based on pairwise or second order probabilities and demonstrate consistency, removing the requirement for asymptotic independence and replacing it with restrictions on higher order selection probabilities. Our approach provides a nearly automated estimation procedure applicable to any model specified by the data analyst. We demonstrate our method on the National Survey on Drug Use and Health.

stat.ME↗