Questions tagged [heterogeneity]

Use this tag for questions in the context of meta-analysis; use [heteroscedasticity] in the context of regression modeling. Heterogeneity arises when the primary studies are not drawn from a single population.

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1answer
446 views

computing heterogeneity assigned to random factors in meta-analysis

I want to calculate the proportion of total variance in a multi-level meta-analysis with 2+ random effect terms according to pp. 1261 & equation (24) in Nakagawa & Santos 2012 https://www....
9
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1answer
30k views

Difference between one-way and two-way fixed effects, and their estimation

Consider a basic linear unobserved effect panel data model, e.g.: $$Y_{it}=\beta x'_{it}+c_i+\lambda_t+u_{it}, \quad t=1,\dots,T$$ where the vector $x_{it}$ contains the independent variables and $u_{...
1
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1answer
461 views

Reporting of Heterogeneity in Metaanalysis

The background is a forest plot of a meta-analysis which is reported to have been calculated with a "random effects model". The pooled effect is reported as a standardized mean difference (SMD). ...
8
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1answer
20k views

Calculating I-squared (in meta-analysis, given tau-squared)

I have results of meta-analysis, which have been carried out and reported. These analyses report tau-squared as a measure of heterogeneity (and the other details from the analysis). I've been asked to ...
6
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2answers
143 views

Identifying the correlation between a slope and a level

Throughout this post, I assume at least second moments exist. Consider a heterogeneous linear treatment effect model of the form: $$Y_i = \alpha_i + \beta_i X_i$$ where $\alpha_i, \beta_i$ are ...
5
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1answer
633 views

Simulation of random-effects meta-analysis yields biased tau^2

I need to realistically simulate study effect sizes and within-study variances for a random-effects meta-analysis in which the outcome is a relative risk. My question: why does this simulation lead to ...
3
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0answers
40 views

Applying Heterogeneous treatment effects to clinical research (non technical explanation)

I'm trying to understand the hype around this estimation of heterogeneous treatment effects in the machine learning literature lately. It seems super interesting, but alot of it is beyond me. I read ...
3
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1answer
833 views

Computation of Network Homophily / Heterogeneity

I am quite confused about the calculation of network homophily in network analysis. Right now I am computing the homophily using the following function, which has been written and also described by ...
1
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1answer
99 views

Heterogeneity test in meta-analysis

In a random effect meta-analysis model with one categorical independent variable $\theta_{ij}=\theta_i+s_j+\epsilon_j$, where $\theta_{ij}$ is the observed effect size in category $i$ in study $j$, $\...
4
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1answer
722 views

Two Study Meta-Analysis: Fixed- vs. Random-effects and heterogeneity

I browsed through several papers and discussion but I am still not sure what is correct. I conducted two studies on the same topic using similar methods and the same design (independent t-tests). ...
3
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1answer
471 views

Meta-analysis: significant heterogeneity vs. significant between-study variance

I am running a simple random-effects meta-analysis in R using the metafor package, with random intercepts at the study level: ...
1
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1answer
43 views

Calculating Effect Size from Wilcoxon W value (how to get the z value)

Im carrying out a meta-analysis where I have had to carry out my own wilcoxon test on the data. I am now calculating the independant effect sizes for each study to manually input to my excel ...
1
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1answer
146 views

How to interpret Cox Model with time-varying coefficients

I fitted a Cox PH Model and upon examination of the Schoenfeld residuals it became apparent that the proportionality assumption was violated by several variables. Following Box-Steffensmeier & ...
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0answers
37 views

Quantifying spatial-temporal variation

Imagine a set of territories each subdivided into 5m grid cells. Each grid cell represents a spatial unit, and that unit can have any number of variables associated with it - e.g. habitat type/subtype,...