Statistical tests help researchers choose the right analysis based on their goals and available data. Cochran's rule compares observed and theoretical numbers. The Kolmogorov–Smirnov test compares two distributions with different types of data. The Shapiro–Wilk test checks if data is normally distributed. The Fisher–Snedecor test tests for equal variances. Bartlett's test checks variances with many repetitions. Levene's test is powerful for comparing variances with different repetitions.