The metric of the cohorts analysis shows, how the conversion rate developed per month since the first visit.

Use the metric with the dimension "Cohorts (Monthly)".

Month 0 = The conversion rate within the first 29 days.

Month 1 = The conversion rate within the 30.-59. days since the first visit.
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CalculationQty Orders (Lifespan Month N) / Visitors (Lifespan Month N) * 100

Extensive information on cohorts in Mapp Intelligence can be found in the corresponding training chapter.