Avg. number of days between two orders.
Formula
Order Time Lag = SUM(DATEDIF(Order Date WHERE Customer Order Count = n+1, Order Date WHERE Customer Order Count = n)) / Gross Orders WHERE Customer Order Count = n+1
Explanation
The Order Time Lag tells you how many days it takes a customer to make his next order.
Notes
The Order Time Lag can be separated into different customer segments.
New Customer Order Time Lag - the average Time Lag between the first and the second order of a customer.
Repeat Customer Order Time Lag - the average Time Lag between the nth and nth+1 order of a customer (where n can't be equal to 1).
Nth Order Time Lag - In some reports you can also select (a range of) repeat orders that you want to filter the Repeat Customer Order Time Lag by. For example, if you select the range from 3 to 6, the KPI will show you how many days it took customers on average between their 3rd and 4th, 4th and 5th, 5th and 6th, 6th and 7th order.
Please note, that only customers that actually placed a next order are used to calculate this metric. Thus, is makes most sense to look at the Order Time Lag in conjunction with the matching Repurchase Rate.
The Repurchase Rate will tell you what percentage of customers placed the next order and the Order Time Lag tells you how many days on average passed between them.