I am computing churn definition i.e, the number of days after which we will say a customer has churned in fashion retail, etc. Currently, I am using the transaction dates to get the average days between two purchases of each customer, other stats such as number of days he has been customer. If anyone has any idea on this , kindly give some pointers.
Perhaps you can define an "active user" (e.g., someone who has made a purchase in the last 3 months, etc. Choose a period sensible for the typical purchase cycle) and calculate the something along the line of DAU or MAU, etc. Say, if a typical active user will on average buy something from your store every 3 months, assume a user has churned if she fails to make a purchase in the last avg + 1sd days, etc.?
The other potential KPI to use is probably the CLV, but similar to DAU and MAU, it is not without its criticisms.