# Statistics Lab / ferdo — synthetic data (no real student records)
# Save stats_synthetic.csv in your working directory.
d <- read.csv("stats_synthetic.csv", stringsAsFactors = TRUE)
stopifnot(nrow(d) == 36, all(c("score_pre","score_post","group") %in% names(d)))
# Groups are observational labels: differences cannot establish a treatment effect.

d <- read.csv("stats_synthetic.csv")
mean(d$score_post)
median(d$score_post)
sd(d$score_post)
IQR(d$score_post)
hist(d$score_post, main="Quiz score distribution", xlab="Post quiz score")
boxplot(score_post ~ group, data=d, ylab="Score")