Variance estimation for volume when D2H is the covariate in regression

1984 ◽  
Vol 14 (6) ◽  
pp. 818-821 ◽  
Author(s):  
H. T. Schreuder ◽  
Jana Anderson
Keyword(s):  
Confidence Intervals ◽  
Loblolly Pine ◽  
Variance Estimation ◽  
Stat Assoc ◽  
Variance Estimators ◽  
Robust Variance ◽  
Variance Estimate

For two realistic (but not real) populations of loblolly pine, variance estimators for weighed regression estimates of total volume are compared. The traditional variance estimators and two robust variance estimators proposed by Royall and Cumberland (R. M. Royall and W. G. Cumberland. 1981. JASA, J. Am. Stat. Assoc. 76: 924–930) are found to be quite unreliable. In contrast, the jackknife variance estimate and confidence intervals based on it are found to be much more reliable.

scholarly journals Multiple-Imputation Variance Estimation in Studies With Missing or Misclassified Inclusion Criteria

2020 ◽  
Vol 189 (12) ◽  
pp. 1628-1632
Author(s):  
Mark J Giganti ◽  
Bryan E Shepherd
Keyword(s):  
Multiple Imputation ◽  
Variance Estimation ◽  
Variance Estimator ◽  
Inclusion Criteria ◽  
Variance Estimators ◽  
Coverage Probabilities ◽  
Log Odds ◽  
Variance Estimate ◽  
High Level ◽  
Analysis Models

Abstract In observational studies using routinely collected data, a variable with a high level of missingness or misclassification may determine whether an observation is included in the analysis. In settings where inclusion criteria are assessed after imputation, the popular multiple-imputation variance estimator proposed by Rubin (“Rubin’s rules” (RR)) is biased due to incompatibility between imputation and analysis models. While alternative approaches exist, most analysts are not familiar with them. Using partially validated data from a human immunodeficiency virus cohort, we illustrate the calculation of an imputation variance estimator proposed by Robins and Wang (RW) in a scenario where the study exclusion criteria are based on a variable that must be imputed. In this motivating example, the corresponding imputation variance estimate for the log odds was 29% smaller using the RW estimator than using the RR estimator. We further compared these 2 variance estimators with a simulation study which showed that coverage probabilities of 95% confidence intervals based on the RR estimator were too high and became worse as more observations were imputed and more subjects were excluded from the analysis. The RW imputation variance estimator performed much better and should be employed when there is incompatibility between imputation and analysis models. We provide analysis code to aid future analysts in implementing this method.

Comparing Instructional Approaches in Caregiver-Implemented Intervention: An Interdisciplinary Systematic Review and Meta-Analysis

2021 ◽  
pp. 105381512198980
Author(s):  
Bailey J. Sone ◽  
Jordan Lee ◽  
Megan Y. Roberts
Keyword(s):  
Adult Learning ◽  
Family Involvement ◽  
Meta Analysis ◽  
Future Research ◽  
Instructional Approaches ◽  
Comparative Efficacy ◽  
Robust Variance ◽  
Analysis Methodology ◽  
Intervention Models ◽  
Variance Estimate

Family involvement is a cornerstone of early intervention (EI). Therefore, positive caregiver outcomes are vital, particularly in caregiver-implemented interventions. As such, caregiver instructional approaches should optimize adult learning. This study investigated the comparative efficacy of coaching and traditional caregiver instruction on caregiver outcomes across EI disciplines. A systematic search for articles was conducted using PRISMA guidelines. Meta-analysis methodology was used to analyze caregiver outcomes, and a robust variance estimate model was used to control for within-study effect size correlations. Seven relevant studies were ultimately included in the analysis. A significant, large effect of coaching on caregiver outcomes was observed compared to other models of instruction ( g = 0.745, SE = 0.125, p = .0013). These results support the adoption of a coaching framework to optimize caregiver outcomes in EI. Future research should examine how coaching and traditional instruction can be used in tiered intervention models with a variety of populations.

Listening Ears or Reading Eyes: A Meta-Analysis of Reading and Listening Comprehension Comparisons

2021 ◽  
pp. 003465432110608
Author(s):  
Virginia Clinton-Lisell
Keyword(s):  
Listening Comprehension ◽  
Variance Estimation ◽  
Meta Analysis ◽  
Age Groups ◽  
Robust Variance ◽  
Reading Condition ◽  
P 16 ◽  
Robust Variance Estimation ◽  
Literal Comprehension

In this study, a meta-analysis of reading and listening comprehension comparisons across age groups was conducted. Based on robust variance estimation (46 studies; N = 4,687), the overall difference between reading and listening comprehension was not reliably different (g = 0.07, p = .23). Reading was beneficial over listening when the reading condition was self-paced (g = 0.13, p = .049) rather than experimenter-paced (g = −0.32, p = .16). Reading also had a benefit when inferential and general comprehension rather than literal comprehension was assessed (g = 0.36, p = .02; g = .15, p = .05; g = −0.01, p = .93, respectively). There was some indication that reading and listening were more similar in languages with transparent orthographies than opaque orthographies (g = 0.001, p = .99; g = 0.10, p = .19, respectively). The findings may be used to inform theories of comprehension about modality influences in that both lower-level skill and affordances vary comparisons of reading and listening comprehension. Moreover, the findings may guide choices of modality; however, both audio and written options are needed for accessible instruction.

Norepinephrine and Vasopressin Compared With Norepinephrine and Epinephrine in Adults With Septic Shock

2019 ◽  
Vol 53 (9) ◽  
pp. 877-885 ◽  
Author(s):  
Bryan E. Menich ◽  
Todd A. Miano ◽  
Gourang P. Patel ◽  
Drayton A. Hammond
Keyword(s):  
Septic Shock ◽  
Propensity Score ◽  
Propensity Scores ◽  
Variance Estimation ◽  
Mortality Rates ◽  
Matched Cohort ◽  
Free Survival ◽  
Entire Cohort ◽  
Robust Variance ◽  
Robust Variance Estimation

Background: The optimal adjuvant vasopressor to norepinephrine in septic shock remains controversial. Objective: To compare durations of shock-free survival between adjuvant vasopressin and epinephrine. Methods: A retrospective, single-center, matched cohort study of adults with septic shock refractory to norepinephrine was conducted. Patients receiving norepinephrine not at target mean arterial pressure (MAP; 65 mm Hg) were initiated on vasopressin or epinephrine to raise MAP to target. Vasopressin-exposed patients were matched to epinephrine-exposed patients using propensity scores. Mortality outcomes were examined using multivariable Poisson regression with robust variance estimation. Results: Of 166 patients, 96 (entire cohort) were included in the propensity score–matched cohort. Shock-free survival durations in the first 7 days were similar between epinephrine- and vasopressin-exposed patients in the matched cohort (median = 13.2 hours, interquartile range [IQR] = 0-121.0, vs median = 41.3 hours, IQR = 0-125.9; P = 0.51). Seven- and 28-day mortality rates were similar in the matched cohort (7-day: 47.9% vs 39.6%, P = 0.35; 28-day: 56.3% vs 58.3%, P = 0.84). Mortality rates were similar between epinephrine- and vasopressin-exposed patients in propensity score–matched regression models with and without adjustments at 7 (relative risk [RR] = 1.28, 95% CI = 0.92-1.79; RR = 1.21, 95% CI = 0.81-1.81) and 28 days (RR = 1.04, 95% CI = 0.81-1.34; RR = 0.96, 95% CI = 0.69-1.34). Conclusion and Relevance: Shock-free survival durations were similar in matched epinephrine- and vasopressin-exposed groups. Adjuvant epinephrine or vasopressin alongside norepinephrine to raise MAP to target requires further investigation.

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