Which key performance indicator measures the change in revenues during a specific period of time?

Customer acquisition cost (CAC) refers to the total cost incurred to acquire a new customer, including marketing and sales expenses. While CAC is an important metric for understanding the efficiency of marketing efforts, it does not measure changes in revenue directly and focuses more on costs rather than income generated.

Cannibalization rate indicates the extent to which a new product eats into the sales of an existing product within the same company. This metric is useful for assessing product performance but does not directly measure overall revenue changes over time, as it focuses on internal product competition rather than total revenue growth.

Average purchase value represents the average amount spent by customers per transaction. While it is a valuable metric for understanding customer spending behavior, it does not capture the overall change in revenues over a specific time frame, as it merely averages transaction values without considering the total revenue growth or decline.