Mathematics
Analysis of Variance (ANOVA)
Quick fact
ANOVA was developed by Ronald Fisher in the 1920s to analyze agricultural experiments, and its name is a bit misleading—it compares means, not variances, by analyzing variance.
Why this is interesting
You want to know if three different fertilizers lead to different crop yields. Why can't you just run multiple t-tests? Because the chance of a false positive skyrockets.