Did the promotion pay? How to measure it fairly
PromotionsSales went up during the promotion. That is not the question. The question is whether you kept more money than you gave away in discount.
Sales going up proves nothing by itself
A promotion almost always lifts sales while it runs. You cut the price, so more people buy. If that were the test, every promotion would be a success.
The real question is smaller and harder: after the discount you gave away, did you end up with more money than you would have had with no promotion at all?
Compare with the weeks before, not with last year
The fairest baseline is your own recent normal: the same days of the week, over the 4 weeks before the promotion started. Last year had different prices, different products and maybe a different festive calendar.
Take the average sales for those weeks. That is roughly what you would have sold anyway. Anything above it is the lift the promotion earned.
Then take the discount off
Here is a made-up example. Normal weekly sales are RM 20,000. During the promotion week they reach RM 24,000, so the lift is RM 4,000. But you gave RM 3,000 in discounts to get there.
The promotion earned RM 1,000 in extra sales, before the cost of the goods. If your margin on that extra RM 4,000 is thin, the promotion may have lost money while looking busy.
Watch the week after
Some promotions only move a purchase forward. Customers who would have bought next week buy this week instead, and the following week dips. Add the week after to your sum before you call it a win.
Run this check on every promotion and a pattern appears quickly: a few mechanics pay every time, and a few never do.