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.
138
questions
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meta-analysis: expected Q and observed Q
I understand the equation for observed $Q$:
$$
\Large
Q = \sum_{i=1}^k \frac{1}{V_i} (Y_i - M)^2
$$
But I don't understand why the expected $Q$ is just the degrees of freedom ($k - 1$), where $k$ is ...
0
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0
answers
17
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Marginal Treatment Effects using MTEFE - postestimation discrepancy
I am currently calculating Marginal Treatment Effects for an outcome Y (earnings) and a treatment D (joining sector 1 vs sector 0), using the MTEFE package from Stata.
I use a separate approach with a ...
- 1
0
votes
2
answers
41
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Testing publication bias and heterogeneity in meta-analysis when using multiple studies
I am conducting a meta-analysis and I'm trying to ascertain how to test for publication bias and heterogeneity.
However, I have used multiple datasets to calculate effect sizes, and therefore I'm ...
0
votes
0
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18
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How to interpret predicted intraindividual variance (residual variance)? [duplicate]
Background
I'm working on a project on modeling/understanding the intraindividual variance of a repeat measurement. To do this, I'm following a tutorial set out by Dr. Nilam Ram that can be found here ...
1
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0
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heterogenous treatment effects - a question
So I conducted a framing experiment - 4000 people received either framing A or B, and donated $ to a charity if they wanted to.
Now I want to check if framing A or B had specific efffects on ...
2
votes
1
answer
78
views
How to check if two segments of an A/B test have significant difference in the treatment effect
I am planning to launch an A/B test and there's a concern about a possible primacy/novelty effect. I've decided to segment users into two segments (New Users, Returning Users) and estimate if the ...
- 203
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0
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16
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Difference in differences to estimate differential impact of treatment?
I'm having some trouble thinking through the implementation of difference-in-differences / if DD is the best approach to use when I am comparing two groups who are both treated, but which I ...
1
vote
0
answers
42
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Best approach to assess meta-analysis heterogeneity when a study has sampling variance of zero
I am currently performing analyses for a meta-analysis looking at the mean difference of pre-post intervention data (i.e., 'mean change'). However, one study reports identical mean and SD for the pre- ...
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3
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1
answer
53
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re: binary random-eff meta-analysis: Why is my heterogeneity estimate so much higher using GLMM compared to other methods? (metabin function)
I am trying to conduct a random effects meta-analysis for binary outcome data using the GLMM method in the meta package (metabin function / meta package).
meta package citation:
Balduzzi S, Rücker G, ...
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0
votes
1
answer
109
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Interpretation of prediction intervals in a random-effects meta-analysis when tau^2 is 0
I'm reading a meta-analysis that compared the risk of an adverse outcome in the intervention and control group. The meta-analysis yielded a summary effect size (risk difference) of +3.9%, with a 95% ...
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1
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0
answers
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Why do tau2 and I2 estimations differ between frequentists and Bayesian models
I was conducting a network metanalysis of treatments and found out that I2 and tau2 esitmates are widely different between the models (as an example, for the same outcome, I have a tau2= 0.0078 and I2=...
- 357
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15
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Variance low and ceiling effect - split by median`?
I heard that a sufficient amount of variance/heterogenity is needed in order to get reasonable results for a correlation test.
Why is that and what solutions exist when variance is too low?
Is ...
- 375
2
votes
1
answer
73
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Pooling the data of longest follow up period vs. performing a subgroup analysis
Im doing a meta-analysis of randomized interventional trials to compare between two types of surgeries.
The follow up period at which outcomes were reported varied between 6 weeks to 24 months. Some ...
- 211
1
vote
1
answer
37
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Can I do a meta-analysis by Monte-Carlo synthetic data?
I'm trying to do a meta analysis of ~30 studies (total N = ~2000) on the correlation (X, Y). However, the heterogeneity is soooo high. My hypothesis (and what has been suggested in the literature) is ...
- 23
1
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0
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15
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How to deal with outliers after heterogeneity test in microarray expression datasets?
I have performed a meta-analysis using five micro-array datasets. After performing meta analysis I visualized the heterogeneity using funnel plot and forest plot (using two up-regulated and two down-...
2
votes
1
answer
127
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Is it more appropriate to use random effect model in meta analysis when studies have high heterogeneity but they are not randomised?
I am using case control studies for a meta analysis. The participation selection is not random but the studies used different statistical analysis methods with their results and there is significant ...
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2
votes
1
answer
65
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Characterizing and comparing the heterogeneity of ordinal responses from survey
Let us consider the following setting:
We have two groups Q1 and Q2 of questions
Several participants answer all questions using a single ordinal scale A, B, C or D for all questions.
Then, I want ...
- 5,043
2
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1
answer
53
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How to tell if a covariate modifies the effect if each subgroup has different number of participants?
Im working on a meta-analysis of interventional studies that compare between two kinds of interventions.
After pooling the studies together, the heterogeneity using I squared was 0%.
Afterwards, I ...
- 211
2
votes
1
answer
47
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Removing studies from subgroup analysis
Im currently working on a meta-analysis of randomized controlled trials, which examine the use of a certain graft in certain surgical intervention. In my pre-specified protocol, I planned to perform a ...
- 211
0
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0
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122
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Control function interact treatment with residual
I am going through an old metrics tutorial using instrumental variables regression. In one question we are supposed to estimate the Average Treatment Effect (ATE) using a control function approach. We ...
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1
vote
1
answer
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What does scale heterogeneity mean in the generalized multinomial logit models?
I have learned that one property of multinomial logit models or the data used to build these models is scale heterogeneity. What does Scale Heterogeneity mean in the sphere of multinomial logit models?...
3
votes
1
answer
73
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How to compute the total standard deviation of the (true) effect sizes, σ, in random/mixed-effects meta-analytic models?
I have the following meta-analytic model (effect sizes nested within samples):
...
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1
vote
0
answers
312
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Econml summary() interpretation [closed]
I just started using EconML library, I would like to ask what does the output of inference summary mean? what exactly is the prediction/inference doing here?
UPDATE: Also, I don't understand about the ...
1
vote
1
answer
38
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Outlier study in a meta-analysis
Im currently working on a meta-analysis of randomized controlled trials (RCTs).
These RCTs have reported their outcomes at different time points.
The maximum follow-up points were as follows: 1 months,...
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1
vote
0
answers
125
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Calculating heterogeneity of groups within a sample
I am currently trying to find the proper statistics measure to calculate the heterogeneity of a group of students. The problem is the following:
I have a population of students, divided into groups of ...
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1
vote
0
answers
407
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Difference-in-difference robust to heterogeneous treatment effect - extension of an article
I am trying to extend the results of Gendron-Carrier et al. (2022) article published in the American Economic Journal : Applied Economics which is about the effect of subway opening on pollution.
I ...
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2
votes
1
answer
463
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Subgroup of one study in a meta-analysis
Im currently working on a meta-analysis of randomized controlled trials (RCTs).
These RCTs have reported their outcomes at different time points.
I decided to split the data of these studies into sub-...
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1
vote
0
answers
36
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Statistical tests on non-homogeneous area
Observing a highly non-homogeneous area, I would like to statistically observe and evaluate certain phenomena. Below is an example set of fields, segmented into 3 zones (Z1, Z2, Z3) using a clustering ...
- 1,353
1
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0
answers
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Seeking help identifying the right causal model for my research
I am conducting a quasi-experimental research where the treatment is of varying intensity. For e.g., to investigate the impact of CEO's transgression on the stock market behavior (hypothetical; not my ...
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1
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0
answers
74
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Is it reasonable to report $I^2=0$ with confidence interval [0, 100] in a meta analysis?
Is it reasonable to report $I^2$=0 with 95% confidence interval [0, 100] in a meta analysis manuscript?
I was not sure since the CI covers all possible values.
$I^2$ is a commonly used heterogeneity ...
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3
votes
2
answers
239
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metafor's rma gives conflicting (zero) values for tauˆ2 and Iˆ2 compared to Review Manager?
I'm having a problem with metafor's rma-function, which inappropriately (I suppose!) gives both tauˆ2 and Iˆ2 zero values. This questions was previously asked on Stack Overflow, and then it was ...
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1
vote
0
answers
70
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Should I expect lower R2 with meta-regression in meta-analyses with low heterogeneity?
The question in short: Should I expect lower R2 values in meta-regression performed in a meta-analysis with low levels of heterogeneity?
In meta-analysis, I2 represents a ratio of between-study ...
- 23
0
votes
1
answer
33
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Can HAR models also be applied on non-volatility data?
Currently, I am trying to forecast several cash flows of accounts receivable and payable of a company. I want to apply the HAR model due to the simple structure of the model; it incorporates the short-...
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3
votes
3
answers
581
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Causal inference where potential outcome is somehow "violated"?
The fundamental problem of causal inference says that only one potential outcome is observed for each unit.
What happens if both outcomes from control and treatment can be observed? Can we still make ...
- 311
1
vote
1
answer
436
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Conditional Average Treatment Effects
Suppose I am interested in understanding the effectiveness of two types of medicine, A and B.
In the usual setting, each patient is considered an experiment unit and is assigned one of the medicines. ...
- 311
0
votes
1
answer
347
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causal tree in a diff-in-diff setting
I am new here. Does anybody know how to set up a causal tree in a diff-in-diff setting with observational data? Is anyone aware of any papers where this has been done?
Any help would be much ...
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0
answers
35
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What Heterogeneity/Between-Study Variance Estimator to use in a Reliability Meta-Analysis/Reliability Generalization Random Effects Model?
This is an extension of this question but for reliability generalization studies.
Could anyone recommend a between-study variance / heterogeneity () estimator and method for computing confidence ...
- 541
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1
answer
271
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How do I write the Jeffreys prior for error variances in stan? $p(\mu, \sigma_1^2, \dots, \sigma_C^2) \propto \Pi{ \sigma_i^{-2}}$ [closed]
I need to model the Jeffreys prior for error variances in a heteroscedastic ANOVA design in rstan.
That is to say, $\pi(\mu,\sigma_1^2,\dotsb,\sigma_C^2)\varpropto\Pi_{i=1}^{C}\sigma_i^{-2}$.
Is the ...
0
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0
answers
45
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What repeated measures statistical tests should I use with uneven sample size and parametrical/nonparametrical distribution?
I'm looking for a way to measure significance + variance homogeneity/heterogenity
First of all I tested my data for normality and it's not always parametrical, so I think that I should use different ...
1
vote
0
answers
65
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What does "sharp design" mean in Chaisemartin (2020)'s paper compared to Goodman-Bacon (2017)'s paper?
When studying the paper of Chaisemartin (2020) comparing to Goodman-Bacon, 2017's paper regarding heterogeneous treatment effects, a commentator said that Chaisermartin's papers have more of a sharp ...
- 549
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vote
0
answers
535
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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)^...
- 11
1
vote
0
answers
105
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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 &...
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0
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222
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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 ...
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1
vote
0
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34
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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 ...
- 11
2
votes
1
answer
439
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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$ ...
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3
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0
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318
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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....
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votes
1
answer
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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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0
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90
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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 ...
- 31
5
votes
1
answer
118
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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 ...
- 18k
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0
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463
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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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