Between-Study Heterogeneity


Slides

Keywords: Cochran’s Q, I-Squared, Prediction Intervals, Outliers, Baujat Plot



Code


# This data set contains effects of studies examining
# the effects of suicide prevention interventions
# Copy and paste the entire code below into your Console.
# Then hit Enter.
data <- structure(
            list(
                study = c("Berry et al.", "DeVries et al.", 
                          "Fleming et al.", "Hunt & Burke", 
                          "McCarthy et al.", "Meijer et al.", 
                          "Rivera et al.", "Watkins et al.", 
                          "Zaytsev et al."), 
                es = c(-0.143, -0.608, -0.111, -0.127, -0.392, 
                       -0.268, 0.012, -0.245, -0.126), 
                se = c(0.147, 0.17, 0.258, 0.176, 0.202, 
                       0.135, 0.183, 0.224, 0.194)), 
                row.names = c(NA, -9L), 
            class = "data.frame")

# Random-Effects Model
# If necessary, install the meta package
install.packages("meta")

# Load the meta package
library(meta)

# Using our 'data' dataset, run metagen:
rem <- metagen(es, se, study, data)
summary(rem)
forest(rem)

# Prediction Intervals
# Set prediction to TRUE
rem <- metagen(es, se, study, data, prediction = TRUE)
summary(rem)
forest(rem)

# Outlier Removal
# Exclude study by de Vries (no. 2)
rem <- metagen(es, se, study, data[-2,], prediction = TRUE)
summary(rem)
forest(rem)
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