Cohort alignment

Reset the clock so every case is measured from its own day zero, then stack those runs side by side. Calendar dates stop being the axis. You compare week four to week four instead of comparing a beginner to a veteran.

Reset the clock so every case is measured from its own day zero, then stack those runs side by side. Calendar dates stop being the axis. You compare week four to week four instead of comparing a beginner to a veteran.

Example

You started lifting in January, your friend in June. On calendar dates her line looks flat next to yours. Replot both by weeks since first workout and her week-six strength gain is actually 2 pounds ahead of where yours was.