Questions tagged [meta-analysis]

Methods focused on contrasting and combining results from different studies, in the hope of increasing precision and external validity.

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correlation co-efficient meta analysis

I am conducting a correlation co-efficient meta analysis. I understand that this involves collection of effect sizes from various data presented in numerous studies. I am wondering What other data ...
136 views

Pooling homogenous studies vs. using meta-analysis/bayesian

I am working with a student who has collected about 300 participants for his thesis. After collecting 100 participants, he analyzed the data. I had just recently read of a "mini-meta-analysis" ...
398 views

why is the log transform of the odds ratio in meta analysis not explicitly described in methods

As we know when analysing the odds ratios in meta analysis we use the log transform of the OR to get the effect size. I think most papers/analyses do this but the log transformation never seems to be ...
166 views

Meta analysis of Multiple regression

I have 10 predictor variables and one outcome variable. However, I used three scales to measure the outcome variable. I conducted three separate regression analysis, with one of the three different ...
76 views

What is the difference between mixed effects and random effects moderator analysis?

Are 'mixed effects' and 'random effects' moderator analyses (meta regression and ANOVAs) used interchangeably? Lipsey and Wilson in 'Practical meta analysis' seem to describe 'mixed effects meta ...
72 views

Meta-analysis: Correlated controls, correlated treatment: How to specify variance-covariance?

Goal The goal is meta-analysis of slope coefficients that I calculate from multiple treatments and controls from multiple studies. I'm looking at the relationship between x broadly and y broadly, ...
105 views

Calculating SD from pre and post mean and their SDs?

I posted this similar question before but I didn't really clarify the values properly. I'm trying to figure out a way to calculate the SD from these below: Mean Pre-operation Glucose 1 = 12.2, SD =...
91 views

Meta-analysis of Odds Ratios and Asymmetric Confidence Intervals

I've come across a series of association studies that report odds and asymmetric confidence intervals. The standard meta-analytic techniques I've used assume symmetrical confidence intervals to ...
31 views

identical results for fixed and random network meta analysis

I performed a network meta-analysis in r package netmeta using the netmeta function and the results are identical for the fixed and random effects analyses. Is this possible or did I do something ...
143 views

How do I find new standard deviation from two means and their SD?

I'm trying to figure out a way to calculate the SD from these below: Mean glucose 1 = 12.2, SD 1=13.5 Mean glucose 2 = 9, SD 2=8.7 % Change in mean glucose = -35.5%, SD = ?? I know calculating % ...
29 views

Using summary statistics from a paper when the original data are not available

There are papers where the authors analyzed data that I would really like to obtain and combine with other data sets in a new analysis. However, because of the age of the papers all I have available ...
109 views

Converting Cohen's d to a Relative Risk for a model-based economic evaluation

Hello researchers: my question is about the use of forest plot results for an economic model. In a forest plot you could have the following results: 0.34 [0.22, 0.45], which would be the pooled ...
128 views

Meta-analysis of regression slope parameter- what is sampling variance?

Goal: Meta-analysis of a regression parameter. My effect size is the slope coefficient of a line, I also have the standard error of this slope. For a given treatment within a given study, the slope ...
548 views

Hazard Ratio Meta-Analysis

I've being reading around the forum and couldn't find exactly what I wanted. I am trying to do an meta-analysis where the HR of each study and the 95% CI were available. I understand variance can be ...
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Does a random effects meta analysis produce the mean of population effect sizes?

In a random effects meta analysis of correlation coefficients, is the outcome the mean of a distribution of population correlation coefficients? If so, is this denoted rho symbol (p) with a hat on? I ...
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Simultaneous network meta-analysis for multiple treatments and outcomes

I am interested in conducting a network meta-analysis (ie mixed treatment comparison) simultaneously pooling effect estimates for multiple treatments and outcomes, within the framework of an umbrella ...
416 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 ...
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What should I enter as n when doing a meta analysis involving correlation coefficients- the number of observations or the sample size?

The r package and function (metafor; escalc) I am using to calculate effect sizes asks for n's (the sample sizes). Should I put the sample sizes of the study or the number of observations that went ...
39 views

How to combine observational studies

I am trying to show the releationship between a drug and an outcome in a particular setting. Using a systematic review, I have found 18 studies addressing this topic. Among those, the highest quality ...
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Interpreting results from moderator analysis in a meta-analysis

In a random-effects meta-analysis I found a negative association between a certain personality trait and gratitude (higher score on personality scale is associated with lower gratitude). Pearson's ...
69 views

Effect size for meta-regression

I have conducted a hierarchical meta-regression, and the results revealed a large R2 with all predictors in the model, which is common in meta-regressions. Some of the non-significant results might be ...
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New Model from average of n-many models

Say I read three studies that predict reaction time based on participants age. I might collect three regression equations with an intercept a slope for age and an error term. After reading three ...
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Summary RR to % risk increase?

In a comprehensive meta-analysis the 'summary RR per 120 g/day increase in red meat intake was 1.20 (95% CI 1.04–1.38)' In a review citing this information, they have written rather 'a 20% increase in ...
70 views

Why am I getting different means when conducting multilevel meta-analysis with factorial moderator vs. as subgroups?

I already asked about this in stackoverflow but maybe it fits better here. I want to conduct a multilevel meta-analysis using metafor in R. I have effect sizes ("esid") nested within samples ("...
248 views

Examples of Change of baseline vs Final values

I'm learning how to perform a meta-analysis from the Cochrane handbook: http://handbook-5-1.cochrane.org/chapter_7/7_7_3_1_post_intervention_versus_change_from_baseline.htm Here they talk about the ...
569 views

Calculating Cohen's d for pre-post/treatment-control design where treatment-control is also a repeated/within factor

I'm conducting a meta-analysis of studies that used pre-post/treatment-control designs. Most of them are mixed designs (pre-post is repeated/within; treatment-control is independent/between) with a ...
62 views

Why do we treat study standard errors as known in a meta-analysis?

I wonder if anyone knows why it is that we treat study standard errors as known when conducting a meta-analysis? When conducting analysis of trial data, the error is treating as a quantity to be ...
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Analysis of Regression Model

I have to apologize in advance for this question. I just want a second opinion. I was given the raw data of a survey. Based on the survey items five factors were created which in combination with ...
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Calculating/Averaging/Aggregating Effect Size Across Multiple Measurements

What is the standard practice for calculating a total effect size (using Cohen's d) across multiple measurements in one study? Do you calculate the effect size for each measurement and then take the ...
606 views

What does the p value mean in meta analysis results output?

What does the p value mean in a meta analysis results output? My meta analysis is looking at the proportion of people affected by PTSD. I am using the software OpenMeta Analyst which runs r in the ...
186 views

Network meta-analysis of diagnostic test accuracy studies

I need to make a network meta-analysis of diagnostic studies. Is there a good explanation to do it with R?
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Meta analysis of test scores in range [0,100]

We have multiple studies of certain test scores which range from 0-100 which we would like to meta-analyze. For each subject within a study a score may vary within this range, however we only have the ...
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Correlational Meta-analysis

I conducted a correlational meta-analysis. There were three groups of behaviours and one aggregate effect size for the correlation between each behaviour group and a continuous measure. We used ...
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Meta-analysis of proportions - how to analyze possible moderators and publication bias?

I am performing a meta-analysis study of proportions in Stata using the metaprop command. My data includes 10 studies for which I have the variables: ...
153 views

Is it ok to add a constant to the means in the log transformed ratio of means?

My colleagues and I were wondering if is OK to add a constant to the means in the log transformed ratio of means (known also as log response ratio). The log response ratio and its variance are: \...
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Literature on combing randomized controlled trials and retrospective studies in meta-analyses

I have read contradictory posts whether randomized controlled trials and retrospective studies can be combined in a meta-analysis. Thus, 1) I am requesting literature on this specific topic (...
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Is it appropriate to pool incidence data from a systematic review for a summary RR?

I have a systematic review to compare incidence of an illness (Y) with or without an intervention (so groups A and B). These groups are relatively homogeneous, so aside from unmeasured confounders I ...
593 views

What are the top five journals in statistics? [closed]

I recently read this article analyzing the top five journals in economics using bibliometrics. I was very interested, and as I'm a PhD student who wants to start publishing, I thought a good project ...
289 views

Do I need to know correlations between dependent effect sizes for multilevel meta-analysis?

I am meta-analyzing with multiple effect sizes from each study. The studies included in my meta-analysis measured the effects of participants REPEATDLY with MULTIPLE TESTS. I am trying to deal with ...
54 views

Effect size calculation

I am conducting a meta-analysis on the diet of predators. This diet is expressed as the proportion of aquatic vs terrestrial prey. I have a value (% of aquatic prey) for each species for each site of ...
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Why aren't common asymmetry tests used to test funnel-plot asymmetry?

In meta-analyses, funnel-plot asymmetry tests are usually based on the association between effect size and its standard error (or variance, that in case of rank-tests are the same) or, alternatively, ...
159 views

Possible to convert intraclass correlation coefficients ($ICC$) for use in meta-analysis of $r$?

I am trying to meta-analyze the validity evidence for a variety of new-fangled measurement devices. My effect size of interest is the correlation (Pearson's $r$) between measurements from these new ...
145 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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Is it more accurate to convert t-test statistic to pearson's r or means and SDs to cohen's d to pearson's r when extracting data for a meta-analysis?

I am completing a meta analysis and the common metric I am using is pearson's r. For studies that report comparisons of means rather than correlations should I convert the t-test statistic the author ...
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Can summary effect sizes from two separate meta-analyses be directly compared?

I have run two separate random effects meta-analyses to estimate summary effect sizes (risk ratios). Both analyses are based on randomized controlled trials examining same treatment for identical ...
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Is there a two-by-two contingency table dataset where an Odds Ratio estimate would work and a Risk Ratio would fail?

I am wondering if there is an example of a two-by-two contingency table dataset where an Odds Ratio estimate would work and a Risk Ratio would fail, or vice versa? In additional are there cases where ...
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In meta-analysis, how can we use l'abbe plots to gauge what effect size we should use?

Typically, in meta-analysis measures like Risk Ratios, Odds Ratios, and even Risk Differences are used to compute effect measures. I am wondering how a l'abbe plot can guide us towards which one to ...
218 views

Minimum number of studies to meta-analyze in random-effects GLM models

I have a question regarding the use of random-effects GLM meta-analytic models and the minimum number of studies needed and its relation to the estimation of $\tau^2$. (I understand that only two ...