Module 02 Summary

What this module established

Five decisions define the analysis: outcome, predictor, grouping, unit and time window. The unit is the one that catches people — the same table analysed per session or per user gives different sample sizes, and every interval and p-value depends on which you meant.

Carry forward

• Complete-case analysis is a decision, not a default. It is valid for the people who answered; whether it says anything about everyone depends on an assumption the data cannot check.
• Repeated measurements from one unit are not independent evidence. Counting them as such always narrows the interval — it never widens it.
• R sets the reference level alphabetically. dose_high sorts before placebo, so a trial silently compares everything to the highest dose.
• Run the check list before the test. A duplicated id or a group of three will not stop t.test() returning a confident answer.

Before moving on

Move on when you can state what one row is, how many distinct units you have, and what your reference level is.

Mark complete