Tagged Questions

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.

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31 views

Calculating the correlation between difference scores from the correlations within timepoints

For a meta-analysis I am conducting, I need to know the correlation between two sets of difference scores. For example, imagine a study in which the researchers measure variables $x$ and $y$ at time ...
3
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1answer
160 views

independent replicate experiments yielding contrasting results

This is a though, simple experiment, for thinking efficiently about a real problem much more complicated... Imagine a simple experiment, trying to answer a simple question. For example, is body ...
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13 views

Meta analysis, joint posterior distribution of study effect

Meta analysis (with common study variation $\sigma$) often assumes that: $$ X_{i,j} | \theta_i \overset{ind}{\sim} N(\theta_i,\sigma)\\ \theta_i \overset{i.i.d.}{\sim} N(\mu,\tau) $$ where ...
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11 views

When is appropriate to combine two treatment groups from one study into a composite whole for a meta-analysis?

The treatment groups I would like to combine appear to be virtually the same, at least by generic label for each group, e.g., groups with the same treatment but implemented at different sites or ...
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28 views

Meta-analysis: design mixed-effects model in R

this is an example of my dataset: ...
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1answer
31 views

Meta analysis: transform forest graph output to percentage effect in R {metafor}

I need the forest graph expressed as % effect. I have run the model with the log ratio, and I know I could back-transform using transf=exp, which would plot the forest graphs expressed as the ratio ...
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21 views

Can Hedges' d be used to compare unlike effects?

I've got a question related to the use of Hedges' d in a meta-analysis of insect fitness information. Here is a link (pdf) to the paper I'm working with. In the appendices, the fitness information ...
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1answer
49 views

nonlinear meta-regression

Can someone point me to a basic explanation of theory and methods for fitting nonlinear curves (particularly quadratic functions) to meta-analytic data? I have a set of effect sizes that are clearly ...
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2answers
29 views

Using variance from a Jeffreys prior in a Prevalence meta-analysis

I am doing a meta-analysis on a group of studies, where the observation is a rate (no. of successes / no of trials). Some of the studies have small sample sizes (n<10) and/or did not observe any ...
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26 views

comparing two sets of meta-analysis

I have two subgroups (high / low BMI) on which several measures where recorded and analyzed on by various papers in a treatment and a control group. I was trying to verify if, for each measure, the ...
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33 views

Meta-analysis: Talking about power and inference (to power)

I need a little help or reassurance concerning how to explain power "to power", i.e. to decision makers that are not well versed in statistics. The problem is this: I have done three empirical ...
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1answer
78 views

Mixed-model meta-regression

I have a collection of continuous data from the literature, including the mean, the standard deviation and the number of observations for both experimental and control groups, as well some ...
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1answer
31 views

Metafor package: RMA and testing for interaction in two studies (Altman & Bland 2003)

I have traditionally used this simple test of interaction (http://www.bmj.com/content/326/7382/219) for comparing effect sizes between studies, and I would like to start performing it in R. Although I ...
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21 views

How big is the risk for regression in a single arm meta-analysis?

I'm performing a single arm meta-analysis of continous data deriving from efficacy evaluation of control gorups surgical procedure. How big is the risk for regression to the mean? And How it could ...
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0answers
86 views

How to deal with unequal sample sizes while fully embrace a dataset?

Imagine the situation: Mythical Seafolk use holes in the seabed as their burrows. Each hole has two parameters - diameter and depth. Majority of holes are unoccupied due to their surplus (n = 235). ...
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55 views

Effect sizes in within-subject design on R

I'm doing a meta-analysis but I need your precious help on couple things : 1) First, on R, in the compute.es package, I found only effect sizes computation formula ...
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1answer
81 views

Oddly large R squared values in meta regression (metafor)

I am using the metafor package in R. I have fit a random effects model with a continuous predictor as follows SIZE=rma(yi=Ds,sei=SE,data=VPPOOLed,mods=~SIZE) ...
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1answer
68 views

Difference between Meta-Analysis, Meta-Regression and Moderator-Analysis

What is the difference between the classic meta-analysis (that aggregates effect sizes from a sample of studies to a summary effect size), meta-regression analysis and moderator analysis? As I ...
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38 views

Independence of effects in meta-analysis and meta-regression

In meta-analysis, I know that an important assumption is independence. Clearly, if we want to estimate a pooled effect size, its best if each effect comes from an independent sample of observers. ...
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23 views

APA-style forest plot using metafor [duplicate]

I have produced a forest plot visualizing results of a meta-analysis, trying to meet the requirements according to the APA style, i.e., statistical terms to be italic, e.g., k = 10, or sub-scripted, ...
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1answer
52 views

computing mean and sd of d-prime from mean and sd of hits and false alarms

I'm working on a meta-analysis. Some studies report d', others report accuracy (hits and false alarms). I would like to transform all the data into the same measure, d' (also c). However, for many ...
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1answer
64 views

Metafor package: Interpreting rma model with two (or more) moderators.

New user of both stackexchange and R here. My questions are about mainly about interpretation, and my dataset is quite large, so I have not included my dataframe. I have two queries (in bold). Using ...
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43 views

Publication bias - trim and fill - macro/syntax

I'm looking for an SPSS or Excel macro/syntax that will allow me to compute Duval and Tweedie’s trim and fill procedure (see paper here: ...
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21 views

How to describe a distribution of statistics in a meta-analysis?

I'm conducting a meta-analysis using water-quality data collected from multiple lakes in multiple regions. Due to the differences in the sampling programs, each waterbody has been sampled an unequal ...
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1answer
58 views

Presenting results of a meta-analysis with multiple moderators?

I wish to present the results of my meta-analysis using the best practices possible. I do not find, however, examples in articles similar to what my output is. Here's a simplification of my model and ...
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25 views

Meta-analysis in R with multiple probes of a microarray

Regarding a question posted here, I have the same problem and I can't figure out a solution. I started by doing my meta-analysis in PLINK, but I want the confidence intervals of the meta-analysis, ...
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59 views

Is there an effect size for Kappa's?

I am staring a project on comparing standard ways of creating a classifier with some heuristic methods. The heuristic methods should result in a faster training for the classifier but should result in ...
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1answer
46 views

Combining two Odds ratios with the same control group

I am doing a meta-analysis of observational studies. As the disease I am working on has different stages, some of the studies reported ORs (95%CI) for each stage separately in comparison to a single ...
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2answers
203 views

Calculating effect sizes and standard errors for the difference between two standardized mean differences

I have two related questions, both of which are related to a meta-analysis I am performing where where the primary outcomes are expressed in terms of the standardized mean difference. My studies have ...
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1answer
376 views

Forest plot for meta-analysis displaying the mean ES with and without outliers

I am conducting a meta-analysis and am trying to produce a forest plot displaying the mean weighted effect size with and without the outliers. I looked on so many websites and tried a lot of syntaxes, ...
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1answer
164 views

Combining data from different sources

I want to combine data from different sources. Let's say I want to estimate a chemical property (e.g. a partitioning coefficient): I have some empirical data, varying due to measurement error around ...
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1answer
75 views

How to perform a meta regression with a random effect model?Which model should I use?How to start? (beginner)

I have to perform a meta-regression, using mixed or random effects model, but I don't have any software (except Matlab) and I'm new on this topic (having a relativelly poor statistics background). ...
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31 views

Meta-analysis with CMA

I wonder if I could ask you all a quick question regarding the input of effect size data into Comprehensive Meta-analysis(CMA)? I have tried contacting via the software portal with no response. I am ...
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1answer
71 views

Extracting data from bivariate vs multivariate analyses for the purposes of meta-analysis

I have what is a very basic question about meta-analysis. If data from individual studies about the relationship of interest are presented in both bivariate and multivariate analyses, which should I ...
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38 views

Does normal distribution assumption improve the quality of results of a meta-analysis of effect-sizes?

Different methods of meta-analysis have different assumptions and one of the popular assumption that has been invoked so often is that of normal distribution. can we work out meta-analytic results ...
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49 views

Meta-analysis of logistic regression

I would like to perform meta-analysis on studies that have a dichotomous outcome measure. I have the raw data for all studies I am including in my meta-analysis, so I can choose the best statistics to ...
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0answers
30 views

What to do with coefficients of log-transformed predictors in meta regression of effect sizes?

I am preparing data for a meta-analysis regression of effect sizes, in which I will study the determinants of effect size for a specific variable across several studies. I have some studies in my ...
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1answer
120 views

convert F-values to effect size

For a meta-analysis I'd like to calculate and aggregate ES-values from studies reporting F-values for mixed model-ANOVA-s. Can you recommend any literature specifically on this topic? +++ After ...
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26 views

If original data are available, should replication data be added and everything re-analysed (IPD) or is a meta-analysis better?

One common practice which increases the odds of obtaining spurious results is to keep collecting observations after a preliminary analyses are performed[1]. This occurs when the cutoff point for ...
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27 views

Moderator Sample Size Discrepancy in Meta Analysis

I'm coding a meta analysis and have come across a paper that seems to have significant variation in the number of participants who answered specific demographic questions. The total sample size is $N ...
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1answer
25 views

Comparing participant numbers in a systematic review

I am doing a systematic literature review on theories for measuring user satisfaction. I have to rate the quality of these theories, and one of the criteria should be the number of participants in the ...
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75 views

Is the approach to moderator analysis advocated by Hunter, Schmidt and Jackson (1982) valid?

There are several approaches, for example, moderated regression analysis and Hunter, Schmidt and Jackson. The HSJ (1982) approach invokes true variance computation based on subsets say male- vs ...
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373 views

Transforming scores between different rating scales – Importance of response options

I'm working on a meta analysis of the mean of a single variable (using arithmetic mean as the effect size, rather than the relationship between two variables). The attitude I'm assessing has been ...
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39 views

Power analysis in meta-analysis: Compute the maximum significance needed by an additional sample for meta-analysis to reach genome-wide significance

I have an association study analysis (GWAS) that does not reach genome-wide significance (max p-value < 10E-5), and there is a potential additional sample (so with known N and known effect size/SE ...
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42 views

What is the unique thing about super-population for a meta-analysis?

The Encyclopedia of survey research indicates that super-population is similar to what may be termed as infinite population. However, in a meta-analysis of effect-sizes, we use outcomes of sample ...
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60 views

Meta-Analysis of GEO data using GEO2R

I'm using data from the GEO and GEO2R online analysis tool provided by NCBI. The GEO2R analysis gives the following scores: adjusted P, P, and t scores. I have 5-10 studies using the GEO2R tool. Is ...
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1answer
124 views

What makes the results differ for fixed-effects models vis-à-vis random effects models?

What makes the results differ for fixed-effects models vis-à-vis random effects models? The Cochrane Collaboration's website indicated that two models can produce different results for a meta ...
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32 views

Meta-analysis with known confounder

I’m performing a meta-analysis in which the main outcome of interest is a correlation coefficient between two variables, $X$ (a psychological measure) and $Y$ (a biomarker). $Y$ is known to be ...
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1answer
109 views

Transform odds ration (OR) in the context of multivariate meta-analysis in R (metafor package)

I would like to conduct a multivariate meta-analysis (multiple treatment arm meta analysis) comparing the effect of different drugs. My outcome measure is discrete and describes the number of ...
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1answer
177 views

Understanding the Meta-analysis Model output in layman terms

I am conducting a meta-analysis from a large number of studies. In each study are compared weights of two groups (fishes with and without internal parasite). I am interested if the weight can explain ...