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#metaanalysis

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Together with colleagues from Spain, we recently conducted a comprehensive simulation study examining the performance of various types of tests and methods for constructing confidence intervals for the scale coefficients in meta-analytic location-scale models. Although things are complex, generally the likelihood-ratio test and corresponding profile-likelihood intervals performed best. See here for further details: doi.org/10.3758/s13428-025-026

SpringerLinkPerformance of location-scale models in meta-analysis: A simulation study - Behavior Research MethodsLocation-scale models in the field of meta-analysis allow researchers to simultaneously study the influence of moderator variables on the mean (location) and variance (scale) of the distribution of true effects. However, the increased complexity of such models can make model fitting challenging. Moreover, the statistical properties of the estimation and inference methods for such models have not been systematically examined in the meta-analytic context. We therefore conducted a Monte Carlo simulation study to compare different estimation methods (maximum or restricted maximum likelihood estimation), significance tests (Wald-type, permutation, and likelihood-ratio tests), and methods for constructing confidence intervals (Wald-type and profile-likelihood intervals) for the scale coefficients of such models. When restricted maximum likelihood estimation was used, slightly closer to nominal rejection rates and narrower confidence intervals were obtained. The permutation test yielded type I error rates closest to the nominal level, whereas the likelihood-ratio test obtained the highest statistical power. In most scenarios, profile-likelihood intervals showed lower coverage probabilities than the Wald-type method but closer to the nominal 95% level. Finally, slightly higher rejection rates and coverage probabilities were obtained when a dichotomous moderator was examined rather than a continuous one. Despite the need to use some constraints on the parameter space for the scale coefficients and the possibility of non-convergence of some procedures that may affect the fitting of the specified models, location-scale models proved to be a valid and useful tool for modeling the heterogeneity parameter in meta-analysis.

#statstab #311 The analysis of continuous data from n-of-1 trials using paired cycles: a simple tutorial

Thoughts: @StephenSenn shows how to treat multiple #nof1 studies as a meta-analysis.

#sced #nof1 #metaanalysis #tutorial #clinical

trialsjournal.biomedcentral.co

BioMed CentralThe analysis of continuous data from n-of-1 trials using paired cycles: a simple tutorial - TrialsN-of-1 trials are defined and the popular paired cycle design is introduced, together with an explanation as to how suitable sequences may be constructed.Various approaches to analysing such trials are explained and illustrated using a simulated data set. It is explained how choosing an appropriate analysis depends on the question one wishes to answer. It is also shown that for a given question, various equivalent approaches to analysis can be found, a fact which may be exploited to expand the possible software routines that may be used.Sets of N-of-1 trials are analogous to sets of parallel group trials. This means that software for carrying out meta-analysis can be used to combine results from N-of-1 trials. In doing so, it is necessary to make one important change, however. Because degrees of freedom for estimating variances for individual subjects will be scarce, it is advisable to estimate local standard errors using pooled variances. How this may be done is explained and fixed and random effect approaches to combining results are illustrated.

In 1993, H. Schwabl published in @PNASNews a seminal paper: “Yolk [as] a source of maternal testosterone for developing birds”

This was the first study proposing a link between maternal egg hormones and fitness.

Our preregistered #systematicreview & #metaanalysis in Ecology Letters synthesises 438 effects from 57 studies on 19 wild 🐦species to test if & how egg hormones relate to fitness

📰 doi.org/10.1111/ele.70100

Data & Code github.com/ASanchez-Tojar/meta

Pre-registration doi.org/10.17605/OSF.IO/KU47W

Another new paper alert. We just published a paper giving a likelihood-based implementation of the Daniels & Hughes bivariate meta-analysis model for surrogate endpoint evaluations (e.g., using progression-free survival as a surrogate for overall survival): doi.org/10.1002/bimj.70048

We propose a bias-adjusted MLE for the variance component of the model, present simulation results, and illustrate the method with a few case studies.

1/3 In a recent paper, we described the use of location-scale models in meta-analysis to not only examine how moderators may be related to the size of the effect, but also how moderators may be related to the amount of heterogeneity among the effects: doi.org/10.1002/jrsm.1562

Such models can be fit with the metafor package in R: wviechtb.github.io/metafor/ref

For those interested in meta-analysis and R:

On the the 'Open Online R Stream' on 2025-03-27 (6pm CET), I will discuss some of the new features in version 4.8-0 of the metafor package.

In the meantime, I will continue with 'Regression and Other Stories' and 'Statistical Rethinking' and do a session on the tinyplot and tidyplots packages.

See wvbauer.com/doku.php/live_stre for details on my weekly live streams.

www.wvbauer.comLive Streams [Wolfgang Viechtbauer]