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Questions tagged [meta-analysis]

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

Meta-analysis refers to methods focused on contrasting and combining results from different studies, in the hope of identifying patterns among study results, sources of disagreement among those results, or other interesting relationships that may come to light in the context of multiple studies.

Some aspects of research that can be meta-analyzed include (credit due to this answer):

  • Heterogeneity of results
    • Moderators (see also )
      • Construct measurement and analytic methods
        • Study quality
      • Population
    • Publication bias
      • Fail safe N – number of null results necessary to reduce an effect size to insignificance

References (credit due to this question: Looking for good introductory treatment of meta-analysis)

- Anglim, J. (2009, December 7). Meta-analysis: Tips, resources, and software. Jeromy Anglim's Blog: Psychology and Statistics. Retrieved from http://jeromyanglim.blogspot.com/2009/12/meta-analysis-tips-resources-and.html.
- Borenstein, M., Hedges, L. V., Higgins, J. P., & Rothstein, H. R. (2011). Introduction to meta-analysis. John Wiley & Sons. Sample chapters available at http://www.meta-analysis-workshops.com/download/bookChapterSample.pdf.
- Dallal, G. E. (2003). Meta analysis. Retrieved from http://www.jerrydallal.com/LHSP/meta.htm.
- DeCoster, J. (2004). Meta-analysis notes. Retrieved February 22, 2014 from http://www.stat-help.com/meta.pdf.
- Egger, M., Smith, G. D., & Altman, D. (Eds.). (2008). Systematic reviews in health care: meta-analysis in context. John Wiley & Sons.
- Harrison, F. (2011). Getting started with meta‐analysis. Methods in Ecology and Evolution, 2(1), 1–10.
- Persuad, R., & Evans, S. (1996). Misleading meta-analysis: "Fail safe N" is a useful mathematical measure of the stability of results. British Medical Journal, 312, 125. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2349768/pdf/bmj00524-0065a.pdf.
- Wolf, F. M. (1986). Meta-analysis: Quantitative methods for research synthesis (Vol. 59). Sage.

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Pros and cons of meta-analyses

I have been considering doing some meta-analysis for a particular field of study in evolution, but before I go any further I would like to know; what are the positives and negatives of the process? For example, no need for a practical experiment is…
rg255
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Question about inverse-variance weighting

Suppose we want to make inference on an unobserved realization $x$ of a random variable $\tilde x$, which is normally distributed with mean $\mu_x$ and variance $\sigma^2_x$. Suppose there is another random variable $\tilde y$ (whose unobserved…
bad_at_math
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How to choose between fixed-effects and random-effects model in meta-analysis?

In meta-analysis packages, both fixed effects and random effects models are available. How do one choose between these two models? Since one is assessing different studies, should one not choose random effects model all the time?
rnso
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Convert hazards ratio to odds ratio

In meta-analysis: How do we convert hazard ratios in some studies to odds ratio? There are case control and cohort studies to be included and some of them report hazard ratios. The raw data is not reported in a way to calculate odds ratio.
Muhammad Ali Khan
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How to conduct a meta-analysis using raw data?

I think meta-analyses are a great way of exploring a hypothesis when available evidence is heterogeneous. Usually however when conducting a meta-analysis one puts aggregated data in a model, possibly losing information. Therefore I am considering…
jokel
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Is it possible to do meta analysis of only two studies

Is it possible to do meta analysis of only two studies. What will be limitation of such analysis.
Rajesh Kumar
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Two studies, opposite results: Am I allowed to compute an overall mean using random-effect model?

I am performing a meta-analysis. I have a subgroup made only of 2 studies and they show opposite results. The 1st has excellent outcomes the 2nd very bad ones. Is it true that I am not allowed to compute the data from these two (different) studies…
Gabriele
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Strange result (v small CIs) using Hartung-Knapp Correction in meta-analysis

I've come across a strange result using a Hartung-Knapp correction (in the metafor::rma() function), when I have a small number of studies, and very similar effect sizes. What I typically expect is that the Hartung-Knapp correction (appropriately)…
Jeremy Miles
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Meta-analysis: is there a way of including dependent effect sizes without averaging across them

I'm running a meta-analysis with a binary outcome (succeed/fail). I am primarily interested on the effect of predictors related to the study (e.g. age of participants, type of task) on the binary outcome, rather than the actual outcome of the study…
user3084100
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Meta Analysis: Pooling samples or determine an average effect size

I am new to meta analysis and how I understood the terminology is that there are actually two ways of performing a meta analysis. Let's consider 5 clinical studies with fixed effects. Fixed effects in terms of the same medical treatment as well as…
Paul
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Small study effects test in presence of sample overlap

I'd like to perform a meta-analysis of treatment effects found across >10 studies, but there are varying degrees of sample overlap between these studies (ranging from 0-35% (relative to larger dataset of given pair)). My understanding is that sample…
Dirptefr
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The trouble with meta-analysing a small number of (homogeneous) single-case studies

I am considering doing a meta-analysis on the reported effects of a particular therapy. I've seen it suggested that the minimum number of studies (so far I identified k=7 of them) is not in itself a hard limitation. However, what I am more concerned…
z8080
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What is the difference between fixed effects model and random effects model for a meta-analysis of sample correlations?

Fixed effects model seems to differ from random effects model for a meta-analysis of sample correlations in terms of assumptions. What is key assumption for a fixed effect model?
user10619
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Is it possible to conduct a meta-analysis on interaction effects from separate linear regression models?

Consider three different studies based on three different datasets. Each of them has a continuous predictor x, a dichotomous predictor z, and a continuous outcome y. In each of these three studies, researchers analyze the x*z interaction on y. Here…
Mark White
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How to combine data several studies with events?

I have a compilation of following data on 10 studies, all of which had 2 groups: a control group which received usual treatment and an active group which received an intervention. The subjects were followed up for one year and any adverse events…
rnso
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