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.
103
questions
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0answers
40 views
How does tau squared (between-study variance) differ for network meta-analysis versus pairwise meta-analysis?
I'm currently trying to replicate a random effects network meta-analysis in Excel.
When estimating between-study heterogeneity, I can calculate Cochran's Q just fine via:
$$Q=\sum w_i(y_i-\hat\theta)^...
0
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0answers
31 views
What is extropy?
While searching for the answer to a statistics problem, I came across the term extropy, which was - and to a large extent still is - unfamiliar to me. A quick google search revealed that it is the &...
3
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0answers
24 views
Multi-level meta-anlaysis
I'm conducting a meta-analysis in which some of studies reported multiple effect size as they examined the outcome on multiple groups of glucose-lowering drugs. So, a three-level meta-analysis was ...
1
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0answers
31 views
Which type of cluster analysis to perform?
I am trying to explain variability in the outcome, and understand factors that may be associated with different clusters? I am confused as to which clustering method to use to obtain 3 clusters as ...
1
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1answer
77 views
EM algorithm for normal mixtures with constraints
I have $G$ groups, each with $N_g$ data points $y_{ig}$, $g=1,\dots,G$ and $i = 1, \dots, N_g$. The group for each data point in observable.
I want to estimate the normal mixtures model with $K$ ...
3
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0answers
22 views
How to choose between different estimators for tau in meta-analysis?
The question is relatively simple although it may won't be possible to answer at all.
In meta-analysis using random-effect model, we can choose between several different methods for estimating tau (e....
0
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0answers
27 views
Estimate both time-variant and time-invariant parameters consistently
We aim at estimating the following model
$$
y_{i t}=x_{i t}^{\prime} \beta+z_{i}^{\prime} \gamma+c_{i}+u_{i t}
$$
where $x_{i t}$ is a vector of time-varying regressors, $z_{i}$ is a vector of time-...
1
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0answers
83 views
What are the QE and QM testing in a meta-analysis, and how do they relate to each other?
I am working on a meta-regression model with a moderator variable (a factor), and so am using the QE and QM tests to explore the importance of the the moderator. I understand the QE tests for residual ...
0
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0answers
18 views
Fixed effect OLS with normalized coefficients in R
I want to estimate the following fixed effects regression:
$$
Y_i = \gamma_{m}+ \lambda_b + \delta_{gb}D_{igb}+\varepsilon_i,
$$
where $\gamma_m$ is municipality fixed effect, $\lambda_b$ is birth ...
0
votes
0answers
4 views
Systematic scoping review search returns studies with heterogenous methods - is it valid? How much method heterogeneity is acceptable?
In a systematic scoping review which returns studies with heterogenous methods, is it valid to include these studies?
In fact, is it correct that a systematic scoping review is the review methodology ...
4
votes
1answer
61 views
Clustering on n features while maximizing the heterogeneity on m remaining features
We have a random vector $X\sim p(X)$, and a set of realizations of the random vector $S=\{X_i\}_{i=1}^N$. The random vector has $n$ continuous and $m$ categorical features. I want to cluster $S$ so ...
0
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0answers
20 views
Continuous (not categorical) measures of diversity?
Which measures of diversity are used where? When I search for diversity indicators I find the Simpson and Shannon index, but these are both for categorical data. If I have data with some structure (e....
2
votes
1answer
149 views
Correct interpretation of Tau and Tau^2 in meta-analysis of different measures
Simple question. Given that Tau is defined as the estimated standard deviation of underlying true effects across studies (and, accordingly, Tau^2 as the variance), how can I interpret this data in ...
6
votes
2answers
152 views
Identifying the correlation between a slope and a level
Throughout this post, I assume at least second moments exist. Consider a heterogeneous linear treatment effect model of the form:
$$Y_i = \alpha_i + \beta_i X_i$$
where $\alpha_i, \beta_i$ are ...
0
votes
1answer
109 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
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0answers
76 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
vote
1answer
52 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
votes
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
42 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
376 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
vote
2answers
41 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
votes
1answer
213 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
96 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
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1answer
219 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
25 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
46 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
votes
0answers
11 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
22 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
vote
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
209 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 ...
3
votes
2answers
48 views
How can I account for heterogeneity at the author level in a meta-analysis?
Suppose that my meta-analysis has several studies performed by the same author. There could be heterogeneity at the author level (because perhaps the author is not very attentive, or uses different ...
1
vote
0answers
27 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
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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
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0answers
110 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
78 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
19 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
41 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
102 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
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0answers
97 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
184 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
344 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
vote
0answers
94 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
373 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
73 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
52 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
103 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
198 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 ...
