Use random assignments to understand how surprising a difference is.
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First lesson in this subject: Read data before calculating
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Four participants score 1, 2, 3 and 4. Conditions A and B were assigned at random, two people per condition. A has 3 and 4, so the mean difference A − B is 3.5 − 1.5 = 2.
Assume neither condition changes anyone’s score. Under this assumption, the same scores could have received different labels. Choose any two of the four participants for A: there are C(4, 2) = 6 equally likely assignments.
You are reading the opening. Members read every lesson and guide in full. A free account reads the first lesson in each subject in full.
You are reading the opening. Your free account reads the first lesson in each subject in full. Members read every lesson and guide in full.
First lesson in this subject: Read data before calculating
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Practice · Shuffle group labels to discover how surprising a difference really is.
Book · Read distributions, question samples, and explore how groups and outliers change a conclusion.
Previous lesson · Investigate influential observations while keeping correlation separate from causation.
Next lesson · Understand what confidence intervals cover, what more data changes and what bias leaves behind.
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