Module 05 Summary

What this module established

A p-value is the share of null worlds that would produce data at least this extreme. H0 is assumed true to compute it, so it cannot be the probability that H0 is true — a simulated null gave 2.39% where the formula gave 2.21%.

Carry forward

• Alpha delivers exactly the false-positive rate you set: 5.01% of true nulls rejected at 0.05. Across twenty tests, the chance of at least one false positive is 65%.
• A one-sided test halves the p-value, which is why the direction must be fixed in advance. Chosen afterwards it makes the real error rate 10%.
• Paired versus independent can decide the result: the same 25 pairs gave p = 0.316 unpaired and p = 1.4e-08 paired.
• A p-value measures evidence against the null, not effect size. A difference seven times smaller had the far smaller p-value.

Before moving on

Move on when your test choice follows from four written answers and every result in your table carries an interval.

Mark complete