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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9 views

What are the QE and QM testing in a meta-analysis, and how do they relate to each other?

I am working on a meta-regression model with a moderator variable (a factor), and so am using the QE and QM tests to explore the importance of the the moderator. I understand the QE tests for residual ...
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13 views

Fixed effect OLS with normalized coefficients in R

I want to estimate the following fixed effects regression: $$ Y_i = \gamma_{m}+ \lambda_b + \delta_{gb}D_{igb}+\varepsilon_i, $$ where $\gamma_m$ is municipality fixed effect, $\lambda_b$ is birth ...
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4 views

Systematic scoping review search returns studies with heterogenous methods - is it valid? How much method heterogeneity is acceptable?

In a systematic scoping review which returns studies with heterogenous methods, is it valid to include these studies? In fact, is it correct that a systematic scoping review is the review methodology ...
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1answer
60 views

Clustering on n features while maximizing the heterogeneity on m remaining features

We have a random vector $X\sim p(X)$, and a set of realizations of the random vector $S=\{X_i\}_{i=1}^N$. The random vector has $n$ continuous and $m$ categorical features. I want to cluster $S$ so ...
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13 views

Continuous (not categorical) measures of diversity?

Which measures of diversity are used where? When I search for diversity indicators I find the Simpson and Shannon index, but these are both for categorical data. If I have data with some structure (e....
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36 views

What is the actual meaning of tau-square uncertainty in bayesian statistics?

I am currently working on a research about bayesian meta-analysis and I understand that the two basic advantages of bayesian model are: 1) it includes prior knowledge and 2) provides uncertainty for ...
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1answer
33 views

Correct interpretation of Tau and Tau^2 in meta-analysis of different measures

Simple question. Given that Tau is defined as the estimated standard deviation of underlying true effects across studies (and, accordingly, Tau^2 as the variance), how can I interpret this data in ...
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2answers
140 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 ...
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1answer
33 views

How can I control for unobserved heterogeneity with cross-sectional data?

I want to run a cross sectional regression for 700 firms in the US to test the impact of working capital on profitability. I specifically want to limit my analysis to the 2008 financial crisis and ...
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41 views

Multi-Factor Kruskal Wallis Test in R

I have a dataset where the response variable is a non-normally distributed proportion and is heterogenous with respect to all factors. I cannot seem to transform the response variable into anything ...
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1answer
34 views

Meta Analysis - Find the pooled Odds Ratio, given each subjects OR, Lower and Upper Limit and Z-test values

I have a problem I have been working on but can't seem to understand how to go about solving, and any help would be most appreciated. My Problem: I have been asked to find the pooled OR and it's 95% ...
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9 views

Can I test whether there is a group of observations in a dataset having a treatment effect in the opposite direction with respect to the ATE?

Suppose that I'm looking for the effect of a shock (for example, a natural disaster, or the current Covid pandemic) on given outcomes, where each observation corresponds to a different person. I ...
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15 views

How to check for heterogeneity over time and location for rate data

I have data that consists of different locations, with repeated observations over time, of counts (and a denominator to make a rate). eg ...
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1answer
29 views

DiD with time invariant and time variant treatment?

I am currently working on a project that seeks to study the impact of the subprime crisis on family firms and non-family firms. In this, I have imagined to use a DiD estimator to account for ...
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2answers
160 views

Heterogeneous Treatment Effects with Continuous Treatment (e.g. using BART)

Overview: Most of the causal inference literature (both theoretical and applied), I have seen on heterogeneous treatment effects, only considers the case with a binary treatment $T\in\{0,1\}$. However,...
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2answers
22 views

Group Heterogeneity in a Meta-Analysis - Layman's Terms

EDIT: I now believe this question was based on misguided information. See my answer. I'm looking through this meta-analysis (of studies on the effects of mindfulness on healthy individuals) for some ...
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110 views

Transforming Heterogeneous Treatment Effect Models (in EconML) into Average Treatment Effect Model (from DoWhy)

This question relates to the steps one would need to take in order to reproduce an answer from the DoWhy tutorial, using the EconML library code for heterogeneous causal effects. In DoWhy, there is ...
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1answer
85 views

Causal inference for multiple treatments with an observed set of properties

Note: I have rewritten this question quite a lot, because pzivich's answer made me realize that I had not formulated it accurately enough . In order to give the original context of pzivich's answer, I ...
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1answer
115 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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1answer
21 views

How to decide if frailty term needed

I´d like to ask the following question: Is there any sound procedure to test event-history/survival data for unobserved heterogeneity or any indicator that shows that a frailty term should be included?...
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1answer
81 views

OLS when $\beta_i$ varies across observations

Suppose that the data generating process is given by $$ y_i=\beta_i x_i+\varepsilon_i $$ where $\varepsilon_i\sim \text{iid }\mathcal{N}\left(0,\sigma^2\right)$. Note that the $\beta_i$ coefficients ...
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1answer
40 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 ...
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10 views

Finite mixture model, nonlinear, parametric, individuals

Suppose that I think individual $i$ chooses number $c$ according to the formula $c = v(f(\delta, \gamma) x - \alpha y))$ where $v$ and $f$ are nonlinear functions. I know what form $v$ and $f$ take. I ...
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0answers
18 views

Hartung-Knapp-Sidik-Jonkman variance correction in meta-analysis

I am doing a meta-analysis of continuous data (SMD), number of studies (k) around 75, heterogeneity high (Tau-squared around 0.15, I-sqr over 75%). Our interest is in fact in a key subgroup analysis (...
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28 views

Equivalence between interaction and second difference measures of heterogeneity

I am trying to understand a paper used by Frank Harrell in his biostats course to demonstrate how NOT to present results from an analysis of heterogeneity of treatment effects (HTE). Frank's point is ...
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2answers
102 views

Meta-analysis: How to interpret a non-significant Q statistic but high I squared

I'm reviewing some meta-analyses on psychotherapies and trying to make sense of the statistics related to heterogeneity, specifically Cochran's Q and the I-squared value. I'm confused about how to ...
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24 views

LOOKING FOR THE OPTIMAL MODEL WITH GAMM

I conducted an experiment where earthworms were subjected to two treatments, with and without herbicide in the soil. Biomass measurements were taken every 12 days for 398 days and the biomass growth ...
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180 views

correlation with diverse characteristics

What does it mean to say "incidental parameter bias due to correlation between past realizations of the data and the unobserved heterogeneity (diverse characteristics)"? How can there be a correlation ...
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0answers
91 views

Difference in Difference heterogeneous treatment effect based on scale of pre-post difference

In a Triple Difference model can we introduce a dummy variable based on scale of difference of dependent variable between pre and post periods? Example: divide both treatment and control groups into 2 ...
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0answers
64 views

One-way ANOVA method validation

Here is my case: Let's say we have 50 polygons(looks like this:and a point set distributed within these 50 polygons. So that for each polygon, there is an associated point density. What I want to test ...
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0answers
15 views

Moderator variable in meta-regression analysis and treatment effect heterogeneity

Meta-regression may reveal that variable A explains heterogeneity in pooled treatment effect of X. In a clinical trial I can investigate whether there is interaction between treatment allocation and ...
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0answers
38 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 ...
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0answers
83 views

Using multinomial logistic regression to test for heterogeneity

I have been asked to use polychotomous logistic regression to test for heterogeneity or independent variable across multiple outcomes levels, and then change-in-estimate method to identify other ...
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0answers
82 views

Looking for R package or function to quantify heterogeneity/homogeneity of groups of character strings [closed]

I’m looking for an R package or function that I can use to measure the relative homogeneity/heterogeneity of groups of character strings. There are about 50 groups, each with thousands of character ...
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149 views

Calculation of I-squared in meta-analysis of diagnostic accuracy

I would like to calculate heterogeneity statistics (Cochran's Q, I-squared) for a meta-analysis of diagnostic accuracy. I successfully used the 'mada' package in R to calculate these statistics, but ...
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1answer
258 views

Conducting a subgroup analysis with regression modeling

I'm conducting a survival analysis using Cox Proportional Hazards regression to identify prognostic factors for cancer patients. My covariates include information such as age, sex, tumor location etc. ...
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0answers
80 views

Why is Metafor R package giving an I2 for fixed effects meta-analysis model (rma.uni)? [closed]

I'm trying to run a fixed effects meta-analysis using the Metafor R package and in the documentation I read that it does not return an I^2 for fixed effects models, only for random effects models. ...
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2answers
328 views

Are there good alternatives to Cochran's Q test for heterogeneity in meta-analysis?

We used the Q test to determine heterogeneity with p-values <0.10. A highly recognised statistician commented that the Q test has low power and that it should not be used to determine presence of ...
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1answer
67 views

Re: Random Effect Model in Binomial Proportions Meta-analysis

I have used a random effects model for the meta-analysis of binomial proportions and have encountered several queries. In one meta-analysis, I have four studies. Sample size of 98, 58, 107, 62 ...
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0answers
50 views

Homogeneity test in survival meta-analysis with adjusted HR

I was wondering what was the way to measure heterogeneity in a survival meta-analysis. I have for each study, an hazard ratio calculated with a penalized cox model (...
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1answer
96 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 $j$, $\...
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3answers
125 views

Is it worth doing (single-armed) meta analysis if the studies' heterogeneity is very large?

I'm currently trying to perform a single-armed meta analysis of immunotherapy on breast cancer, which I believe this meta analysis will be the first among its intervention and cancer subtype. The ...
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0answers
27 views

What heterogeneity test is appropriate for my study? And, what is the use of correlation between median PFS and median OS [duplicate]

I want to perform a meta analysis of a particular subjects of cancer. My effect sizes are Overall Response Rate (ORR), Disease Control Rate (DCR), Duration of Response (DOR), Progression-Free Survival ...
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1answer
156 views

How to correct standard errors for heterogeneity and intra-group correlation?

I got my article manuscript back from review and one notion from a reviewer was that in my analyses "[s]tandard errors are not corrected for heterogeneity or intra-group correlation", s/he apparently ...
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0answers
42 views

I squared for measuring homogeneity

I can't seem to find a simple resource that explains what I can use the I2 (derived from Cochrane's Q), often used in meta-analyses for, exactly. Most, if not all resources I find on the subject go on ...
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1answer
32 views

In meta-analysis Q-statistic, is there a better way to compute the degrees of freedom?

I am working with a meta-analysis, and attempting to quantify heterogeneity across several data sources. I am using the following formula: $Q = \sum_i(w_i \cdot (y_i - \mu_F)^2)$ where $y_i$ is the ...
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0answers
249 views

Fixed or random effects in a subgroup analysis where heterogeneity is present in one of the subgroups but not the overall pooled result?

I am looking at a meta-analysis where a subgroup analysis has been performed, as it is important to consider the treatment effect within 2 subgroups of interest, as well as the overall pooled result. ...
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0answers
35 views

Deriving heterogeneity measures for each level in a multi-level moderator meta-analysis

I'm running a multi-level moderator meta-analysis using the R package metafor. To derive $I^2$ for the metafor analysis as a whole, which doesn't come out ...
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3answers
607 views

Calculating Standard Error of Tau - Meta Analysis

I am conducting a meta analysis using the metafor package in R and am trying to calculate the Standard Error (if possible) of the Tau statistic. The S.E of the tau-...
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0answers
320 views

Using metafor with multiple outcomes from single studies, and how to calculate within- and between-study heterogeneity?

I am currently conducting a meta-analysis where we have several studies that report multiple outcomes from the same participants. We've been advised to use the ...