The Cohort Analysis Helper

Help me analyse behaviour by cohort to see what's really happening over
time.

The metric and cohorts: [E.G. RETENTION BY SIGN-UP MONTH, SPEND BY
ACQUISITION CHANNEL]
The data: [DESCRIBE OR PASTE]

Provide:
1. How to structure the cohort analysis for my question
2. What the pattern across cohorts reveals that an aggregate number hides
   (are newer cohorts better or worse?)
3. Whether the business is genuinely improving or just growing
4. The cohort signals of a healthy vs deteriorating business
5. What to investigate about the best and worst cohorts

Show me how cohorts expose trends that blended averages disguise.