Face serums: the more expensive the product, the better discounts work

All six sizes produced a demonstrable effect, which is rare — in most categories the small and the very deep changes disappear into noise. Here the curve simply keeps going: 16 percent better rank for a small discount, 22 percent for a moderate one, 31 percent for a quarter off or more. On the increase side the cost grows the same way, from 17 percent worse for a small rise to 37 percent for a large one.

What this rules out is a discount ceiling. In other categories a cut beyond roughly a quarter buys nothing extra. In serums it still does — which does not make deep discounting profitable, only effective. Whether it pays depends on margin, and that is a calculation per product, not per category.

Across 6,246 price changes from 495 products, three quarters of all moves were answered on the same day and 70 percent of the remaining answers arrived the next. This is a category run by automated repricing.

The practical consequence: a price advantage in serums lasts hours, not weeks. Discounts here are campaigns with an end date. And increases are slightly more likely to be followed than cuts, so raising a price is a less lonely move than it feels.

Only two of twelve price ranges clear that baseline, and the corridor at €11.19 to €14.11 is the stronger of them: 33 products, of which almost half rank in the top third, a typical review count of 77 against 229 one range above, and 9 of 16 recent entrants winning or building. Prices there hold for about six weeks, so a newcomer should budget for regular repricing.

Two honest qualifications. First, part of the demand evidence in that range rests on one established product carrying 10,037 reviews against a band median of 77 — its success comes from brand equity, not from the price position. Second, that corridor sits in the budget tier, which this report shows to be the least price-responsive part of the category. Entering there means competing on product and visibility, and holding price rather than discounting into the market.

Worth knowing about this category as a whole: of 697 priced products, 436 launched within the last two years, 91 of them have already reached the top third and only 10 disappeared. Serums take newcomers.

Of 7,100 price changes found, 1,257 had another change from the same product running in the same window — nearly one in five moves happens inside its own turbulence. Another 647 coincided with a burst of new reviews and 327 with a stockout; both move rank on their own, so they are excluded. 313 events were dropped because the product was already sliding before the price came down, which is a seller reacting to a problem rather than causing an effect.

Two more numbers describe the category. The observed price changes run from 76 percent off to more than tripling, so this is not a market with settled prices. And 164 of the 861 products listed under serums do not sit in that branch of Amazon's own category tree — 854 of their events are excluded from every figure here.

861 products on amazon.de, taken from the category listing and then narrowed: no multipacks or gift sets, no ampoules, no eye or body products, no face oils, no creams or masks that were listed under serums, nothing below €6 or above €90, container sizes between 15 and 75 ml where stated, and at most eight listings per brand so that a single seller's catalogue cannot dominate the control groups. Products that Amazon does not place in the serum branch are flagged automatically and excluded from all figures. The product list is available on request for methodological review.