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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8 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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11 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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0answers
25 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
31 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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0answers
14 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
49 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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40 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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9 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
32 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
56 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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65 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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77 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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18 views
Heterogeneity in pooled cross sectional data
Hey I'm trying to estimate the effect of minimum wage changes on unemployment using data from the American Community Survey.
Since the ACS is pooled cross sectional data, the sample which is ...
2
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1answer
134 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
54 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
195 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
44 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
38 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
81 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
70 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
24 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
128 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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37 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
194 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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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
425 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
214 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 ...
2
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2answers
333 views
How to interpret heterogeneity in a meta analytic model
I try to fit a random effects model for my thesis, a meta analysis of studies about team planning and team performance.
I'm using R and the package metafor to create z correlations and variance (yi, ...
3
votes
1answer
546 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 ...
2
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1answer
78 views
proportional meta-analysis, small confidence intervals and I square of 100 %?
I am performing a meta-analysis of proportions, I have data about the number of cases and the total sample sizes.
I will be using the Freeman-Tukey double arcsine (Freeman & Tukey, 1950; Miller, ...
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1answer
59 views
Meta analysis: is there such a thing as too little heterogeneity?
First time I've seen results like these and they make me feel uneasy. Is it even appropriate to do a meta-analysis here? Even my poor forest and funnel plots are messed up.
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1answer
506 views
Panel regression with multiple fixed effects and heterogeneity
For a research project I am supposed to estimate a panel regression model on a dataset with user data over observation time (the sample is assumed to represent general population). The supervisor is ...
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1answer
306 views
Testing for treatment effect hetereogeneity in regression discontinuity design
I am not a statistician or econometrician, so please bear with me. For a term paper, I am estimating local treatment effects using a regression discontinuity design, and I want to test whether the ...
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0answers
1k views
Heckman selection model for unbalanced panel data
I want to apply a heckman sample selection model (implemented for example in the R package sampleSelection, see here). However I have an unbalanced panel with ...
3
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1answer
609 views
How do I calculate confidence intervals for I-squared in order to assess heterogeneity between two pooled studies?
I am conducting a meta analysis and for some of my pooled data, there are only two studies available. Based on this publication I have been calculating confidence intervals around I-squared in order ...
3
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2answers
296 views
I-Squared: From Calculation to Concept
In meta-analyses, it's common to report the I-Squared statistic as a measure of heterogeneity of results across studies. The definition given by Higgens 2003 as "the percentage of total variation ...
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1answer
46 views
Regression: OLS: residual split
A friend of mine is estimating the following model, using ols:
$y=\alpha + \beta X + u$,
where $y$ and $X$ are continious variables, $\alpha$ and $\beta$ are parameters and $u$ is an error ...
2
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1answer
175 views
Intuition on simple linear regression signal plus noise model
I'm currently studying linear regression on this book
"F.M. Dekking - A Modern Introduction to Probability and Statistics: Understanding Why and How" where the signal+noise model is presented:
$Y_i =...
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0answers
64 views
Framework for simulating SEM data w/ moderation + mediation, testing models
I'm interested in extrapolating treatment effects from RCTs to new populations under conditions where populations exhibit relevant differences that induce differences in treatment effects.
My aim is ...
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1answer
505 views
How to analyse unbalanced panel data with attrition and defiers?
I'm working with a panel data from a quasi-experimental study with the following characteristics
1) Unbalanced covariates between the control and the treatment group (according to Hotelling's T-...
4
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1answer
638 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
272 views
Clarification of LLNs when non i.i.d. observations
I have a question on how to interpret Law of Large Numbers. Its meaning seems to me clear when we are in the i.i.d. case:
Consider $(Y_i)_{i=1}^n$ i.i.d. random variables with $\mu\equiv E(Y_1)<\...
2
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1answer
375 views
Heterogeneous treatment effects with 2SLS local average treatment effect (LATE)
I am interested in a strategy to calculate heterogeneous treatment effects with an IV strategy for local average treatment effects (LATE).
I am estimating the effect of postsecondary educational ...
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1answer
23k 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_{...
2
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1answer
185 views
How to deal with unexpected low heterogeneity in meta-analysis?
I am performing a meta-analysis in R with metafor package. Primary studies report the reduction of plant species to certain amount of nitrogen fertilization. Effect ...
3
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1answer
389 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:
...
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0answers
28 views
Quantifying group homogeneity
I'm trying to find a way to quantify the homogeneity of a group.
An example dataset is below, where group D, for example, has 5 members of type1, 1 member of type2, and 1 member of type3. Groups A ...
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1answer
296 views
influence of number of observations on entropy calculation
I am performing a genomic study where I am interested in determining the heterogeneity of epigenetic alleles (DNA methylation patterns) in specific genomic locations. Previous work on this subject has ...
