Criterion for the simultaneous selection of a working correlation structure and either generalized estimating equations or the quadratic inference function approach

Westgate, Philip M.

doi:10.1002/bimj.201300098

Cited by 20 publications

(17 citation statements)

References 36 publications

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“…Theoretically, the QIF approach is equally or more efficient than GEE. However, finite-sample covariance inflation of the regression parameter estimates must be taken into account, as is done in Westgate [19, 20]. Westgate [20] proposed a method that utilizes the TECM to select both a working correlation structure and one of these two methods, analogous to the approach we used in this manuscript.…”

Section: Discussionmentioning

confidence: 99%

“…However, finite-sample covariance inflation of the regression parameter estimates must be taken into account, as is done in Westgate [19, 20]. Westgate [20] proposed a method that utilizes the TECM to select both a working correlation structure and one of these two methods, analogous to the approach we used in this manuscript. Therefore, our study results imply that the covariance inflation correction can also be used with GEE incorporating structured working correlation matrices in the context of Westgate [20].…”

Section: Discussionmentioning

confidence: 99%

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A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: a study on its applicability with structured correlation matrices

Westgate

2015

Journal of Statistical Computation and Simulation

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When generalized estimating equations (GEE) incorporate an unstructured working correlation matrix, the variances of regression parameter estimates can inflate due to the estimation of the correlation parameters. In previous work, an approximation for this inflation that results in a corrected version of the sandwich formula for the covariance matrix of regression parameter estimates was derived. Use of this correction for correlation structure selection also reduces the over-selection of the unstructured working correlation matrix. In this manuscript, we conduct a simulation study to demonstrate that an increase in variances of regression parameter estimates can occur when GEE incorporates structured working correlation matrices as well. Correspondingly, we show the ability of the corrected version of the sandwich formula to improve the validity of inference and correlation structure selection. We also study the relative influences of two popular corrections to a different source of bias in the empirical sandwich covariance estimator.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: a study on its applicability with structured correlation matrices

Westgate

2015

Journal of Statistical Computation and Simulation

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“…GEE approach is often used in longitudinal data analysis, while this method behaves robustly against misspecification of the working correlation structure. 43,44 The GEE method was used to account for the repeated longitudinal nature of patients on both primary outcomes because some patients had more than two visits within the study period. We began with unadjusted analysis of associations between odds of admission, with each of the patient demographic and clinical characteristics listed above and then repeated this analysis for the second outcome of unplanned ED revisit within 72 hours.…”

Section: Methodsmentioning

confidence: 99%

The Association Between Limited English Proficiency and Unplanned Emergency Department Revisit Within 72 Hours

Ngai

Grudzen

Lee

et al. 2016

Annals of Emergency Medicine

117

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Study Objective-Language barriers are known to negatively impact many health outcomes among limited English proficiency (LEP) patient populations, but little is known about the quality of care LEP patients receive in the Emergency Department (ED). This study seeks to determine if LEP patients experience different quality of care than English speaking patients in the ED, using unplanned revisit within 72 hours as a surrogate quality indicator.Methods-We conducted a retrospective cohort from an urban adult ED in calendar year 2012; with a total of 41,772 patients and 56,821 ED visits. We compared 2,943 limited English proficiency patients with 38,829 English speaking patients presenting to ED after excluding patients with psychiatric complaints, altered mental status, non-verbal states, and patients with more than four ED visits in 12 months. Two main outcomes-the risk of inpatient admission from the ED, and risk of unplanned ED revisit within 72 hours-were measured using odds ratios from generalized estimating equation multivariate models.Author Contributions KMN, LDR, and AF were responsible for conception and design of the study. LDR and AF supervised the conduct of the study. KMN managed the data. KMN and RL provided statistical advice on study design and analyzed the data. KMN and AL drafted the article, and all authors contributed substantially to its revision. KMN takes responsibility for the paper as a whole. MeetingsWe presented an earlier version of the results as a poster at Society for Academic Emergency Medicine Annual Meeting in Dallas, Texas, in May 2014. Conflicts of InterestAll authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptResults-LEP patients were more likely than English speakers to be admitted (32.0% vs. 27.2%, OR 1.20, 95% CI 1.11-1.30), this association became non-significant after adjustments (OR=1.04, 95% CI 0.95-1.15). 32,857 patients with 45,546 ED visits were included in the ED revisit within 72 hours analysis. 4.2% of all patients (n=1,380) had at least one unplanned revisit. LEP patients were more likely than English speakers to have an unplanned revisit (5.0% vs. 4.1%, OR=1.19, 95% CI 1.02-1.45). This association persisted (OR=1.24, 95% CI 1.02-1.53) after adjustment for potential confounders including insurance status.Conclusions-We found no difference in hospital admission rates between limited English proficiency patients...

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“…62 More recent work by Westgate 63,64 provides improvements by using a bias-corrected sandwich covariance estimate and by simultaneously selecting the QIF or GEE while selecting the best working correlation structure. 65 Despite the many attractive properties of QIF, at this time there are few applications in public health. 66–68 …”

Section: Developments In the Analysis Of Parallel Group-randomized Trmentioning

confidence: 99%

Review of Recent Methodological Developments in Group-Randomized Trials: Part 2—Analysis

et al. 2017

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In 2004, Murray et al. published a review of methodological developments in both the design and analysis of group-randomized trials (GRTs). Over the last 13 years, there have been many developments in both areas. The goal of the current paper is to review developments in analysis, with a companion paper to focus on developments in design. As a pair, these papers update the 2004 review. This analysis paper includes developments in topics included in the earlier review, such as methods for parallel-arm GRTs, inference for conditional and marginal effects, and new topics including methods to account for multiple levels of clustering and alternative estimation methods such as augmented GEE, targeted maximum likelihood and quadratic inference functions. We also examine developments in dealing with missing outcome data, including doubly robust approaches, software available for analysis, and analysis of alternative group designs (including stepped wedge GRTs, network-randomized trials, pseudo-cluster randomized trials and individually-randomized group treatment trials). These alternative designs, like the parallel-arm GRT, require clustering to be accounted for in both their design and analysis.

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Criterion for the simultaneous selection of a working correlation structure and either generalized estimating equations or the quadratic inference function approach

Cited by 20 publications

References 36 publications

A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: a study on its applicability with structured correlation matrices

A covariance correction that accounts for correlation estimation to improve finite-sample inference with generalized estimating equations: a study on its applicability with structured correlation matrices

The Association Between Limited English Proficiency and Unplanned Emergency Department Revisit Within 72 Hours

Review of Recent Methodological Developments in Group-Randomized Trials: Part 2—Analysis

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