Field note · 4 March 2026
Threshold promotions and the quiet basket ceiling
Spend-and-save lines can teach customers to stop just short. Here is how AOV charts reveal that habit.
A £40 spend-and-save sounds generous until the basket histogram shows a spike at £38–£39. Customers learn the line and park just under it when the reward feels optional. Average order value then stalls even while traffic looks healthy.
In a threshold lens chart we count baskets in narrow bands around the line, before and after the mechanic launches. A growing cluster immediately below the threshold is a signal to raise the reward, lower the line, or retire the mechanic for a quieter trading stretch.
This is one of the few places where a distribution view beats a single average. The average hides the pile-up; the bands make it obvious in a merchandising meeting.