How much will existing customers purchase next?

Fit BG/NBD and Gamma–Gamma, then evaluate against later observed purchases. Declare the observation window or study design before running. The result includes denominators and leaves unidentified quantities uncomputed.

Required data: Transaction ID · Order ID · Customer ID · Transaction timestamp · Net revenue after discounts/refunds · Variable cost · Currency code

Assumes noncontractual purchases, positive order values and frequency–value independence. Mean intervals are not individual predictive intervals.