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.
95
questions
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0answers
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 ...
0
votes
0answers
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 ...
0
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0answers
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 ...
4
votes
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 ...
0
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0answers
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....
0
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0answers
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 ...
1
vote
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 ...
6
votes
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 ...
0
votes
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 ...
1
vote
0answers
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 ...
1
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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% ...
1
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0answers
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 ...
0
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0answers
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
...
1
vote
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 ...
8
votes
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,...
1
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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 ...
0
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0answers
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 ...
3
votes
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 ...
1
vote
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 & ...
0
votes
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?...
1
vote
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 ...
1
vote
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 ...
0
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0answers
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 ...
1
vote
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 (...
1
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0answers
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 ...
2
votes
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 ...
1
vote
0answers
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 ...
1
vote
0answers
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 ...
2
votes
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 ...
1
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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 ...
1
vote
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 ...
3
votes
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 ...
0
votes
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 ...
1
vote
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 ...
1
vote
0answers
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 ...
3
votes
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. ...
1
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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. ...
2
votes
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 ...
2
votes
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
...
2
votes
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 (...
1
vote
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 $j$, $\...
2
votes
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 ...
2
votes
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
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 ...
1
vote
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.
...
1
vote
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 ...
3
votes
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-...
1
vote
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 ...
