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.
0
votes
0answers
14 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
28 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
31 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
23 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 ...
0
votes
0answers
2 views
Double-bounded dichotomous choice
I need help. I am using a Double-bounded dichotomous choice model and I do not find tests of heteroscedasticity or tests for the assumption of linear relationship between the logit of the result and ...
3
votes
3answers
102 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-...
0
votes
0answers
21 views
observed heterogeneity in mixed logit model with R
Is anyone aware of a R package which accounts for observed and unobserved heterogeneity across individuals in the random coefficients of a mixed logit model simultaneously, except the ...
1
vote
0answers
35 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
votes
2answers
53 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, ...
1
vote
1answer
76 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
votes
1answer
41 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, ...
1
vote
1answer
46 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.
...
0
votes
1answer
51 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 ...
0
votes
0answers
6 views
Intratumor heterogenity in ordinal scaled histology dataset? Cluster analysis for non independent observations?
I got my hands on a histology dataset and we want to analyze the heterogenity within brain tumors. My current but growing dataset contains 116 records from 29 patients.
The tissues are dyed and ...
1
vote
1answer
81 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 ...
1
vote
0answers
320 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 ...
1
vote
1answer
187 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 ...
0
votes
0answers
44 views
How to measure spatial heterogeneity?
One approach to measure spatial autocorrelation is calculating Moran's I.
How can I measure spatial heterogeneity?
Could it be a consequence of spatial heterogeneity if the residuals of a model are ...
3
votes
2answers
100 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 ...
1
vote
1answer
39 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
votes
1answer
96 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 =...
2
votes
0answers
44 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 ...
1
vote
1answer
273 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
votes
1answer
397 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). ...
2
votes
1answer
109 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
votes
1answer
175 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 ...
3
votes
1answer
12k 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
votes
1answer
156 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
votes
1answer
274 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
vote
0answers
24 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 ...
1
vote
1answer
140 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 ...
4
votes
1answer
437 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 ...
1
vote
0answers
321 views
Heterogeneity testing in logistic regression models
We ran 5 separate logistic regression models testing a set of independent variables on 5 different country-specific datasets. Our goal was to assess the relative contributions of known risk factors of ...
0
votes
1answer
82 views
Measure heterogeneity among multiple samples and scale variables
I would like to know what are the available statistical measures for quantifying heterogeneity on data that look like this...
...
2
votes
0answers
124 views
2SLS with heterogeneous first-stage
Suppose I have the following model, where $c$ indexes group and $i$ indexes members within a group. The sample is made up of $(i,c)$ pairs. The model is:
$$
y_{ic} = \alpha + \beta_x x_i + \epsilon_i ...
1
vote
1answer
346 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).
...
2
votes
1answer
173 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....
0
votes
1answer
117 views
CSTS dataset - robust standard errors lead to big drop in t-values
I am running a regression on a Cross section time series data set (cross sectional dominant) that has the following characteristics:
1,200 cross sections (6 countries * 200 products). Each country - ...
0
votes
1answer
722 views
Multiple Time Fixed Effects in Panel Regression
I have weekly panel data for more than a hundred cities. The independent variables are temperature and precipitation. The time dimensions; year, month, and week - likely have time invariant ...
0
votes
1answer
59 views
Detecting heterogeneity in simple data set
I have a data set with an amount of tests that were done by a group of people for each day over two weeks (no weekends). Basically, I need to know which days differ the most from others. Here is the ...
3
votes
1answer
2k views
Q-Test of Heterogeneity for only two effect sizes?
I am using the Q-Test of Heterogeneity to investigate if several effect sizes derived from two different studies are significantly different from each other.
More precisely, I have, for every effect ...
1
vote
0answers
34 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,...
1
vote
0answers
86 views
Explanation of heterogeneity [duplicate]
Following is the output of meta-analysis of five fictitious studies:
...
0
votes
2answers
112 views
Creating heterogeneous risk score groups (risk based groups on the score)
I just built a credit risk score model (using logistic regression).
Now that I have all estimates and resulting score per observation I would like to create risk groups, e.g.: 10 risk groups where 1 ...
1
vote
0answers
101 views
Heterogeneity measures when pooling meta-analyses: what assumptions do we make?
I am looking at the possibilities and limitations of meta-meta-analysis (MMA), put differently, pooling the results of multiple meta-analysis. I realise that it is better to include primary studies, ...
1
vote
0answers
19 views
Confirm heterogeneity in a fish population over time
For my thesis I have to statistically prove that heterogeneity is establishing over time, more specific in the weights of a fish population.
My dataset consists out of the weights of 17fish and the ...
3
votes
1answer
1k views
Calculating heterogeneity (Cochrane $Q$ and $I^2$ statistics) in random effects model
I want to ask whether I can calculate the Cochrane $Q$ and $I^2$ statistics in a random effect model.
I collected some data from different areas and want to compare the prevalence of allergic ...
2
votes
0answers
58 views
Quantifying tree height diversity or heterogeneity
I am analyzing data collected in the field for a habitat selection study of a large mammal. I have ~1300 plots that were sampled. I am trying to find a good way to quantify the diversity of tree ...
2
votes
0answers
69 views
Finding the median distribution of many distributions?
I have many customers. Each generates his own distribution of shopping times. Each customer thus has their own empirical distribution of shopping times.
If I want to get a sense of the average ...
2
votes
1answer
107 views
Is there such thing as correlation trees? Clustering rows of X based on correlation between A and B
I have been searching for several days for a method that fits this description, though cannot find one. I'm pretty sure it must exist.
The problem (short version):
I'd like to run something like a ...
