meta_example

library(metafor)
library(dplyr)

# sample size per study
n <- 10

# population effect size
true_d <- 0.2

# generate studies
data <- data.frame(
  study = rep(c("a", "b", "c", "d", "e", "f", "g"), 
              each = n), 
  dv = rnorm(n = n * 7, mean = true_d)
)

# calculate summary statstics 
data <- data %>% 
  group_by(study) %>% 
  summarise(mean = mean(dv), se = sd(dv) / sqrt(n))

# conduct and plot the meta analysis
ma_out <- rma(data = data, yi = mean, sei = se, slab = data$study)
forest(ma_out)