Percentages from testing: how to read “hydration increased by 76%”
Korean manufacturers readily cite precise figures for improvement. To understand what they mean, you need to know three things: how many participants there were, who ran the test and what the comparison was made against.
“Hydration increased by 76.26 percent.” “Itching decreased by 46.48 percent.” Figures like these appear constantly in descriptions of Korean products, and they look rigorous: accurate to the hundredth, so something must have been measured with instruments.
Something was indeed measured. But to understand what the number actually means, you need to ask three questions, and none of them is about the figure itself.
Three different types of testing
Korean materials most often contain three things, and they are easy to confuse.
A human application test is instrumental measurement on volunteers: hydration with a corneometer, roughness with a profilometer, redness with a camera. Usually twenty to thirty participants, over a period of two to four weeks. This is not a clinical trial of a medicine but an instrumental check of a cosmetic effect.
A clinical trial is a term from the world of medicine, with a control group, blinding and statistics. In cosmetics it is rare and costs money of an entirely different order.
A consumer survey is when people were asked whether they liked the product. Figures such as “100 percent of participants noted” almost always come from here. This is an opinion, not a measurement, and it must not be presented as proof of an effect.
What to ask
How many participants there were. Twenty is normal for cosmetics, but it is few for broad conclusions, and it is more honest to say so straight away. Who ran the test: an in-house laboratory or an independent centre, and whether it holds accreditation. What the duration was and what the comparison was made against: the condition before the start, or an untreated area of skin.
The most useful step is to ask for the report itself. Serious manufacturers release it for a specific deal or for registration on the market. The report shows both the method and the spread of values, and the spread says no less than the average.
For instance, AGERIN cites a study of its exfoliating gel dated July 22, 2025 with twenty female participants, carried out by an independent laboratory, and the result is given with its spread. A spread alongside the average is a good sign: it means the figure was not rounded into something pretty.
How to present this to your own customer
Carry the figure together with its origin. “According to the manufacturer, in a human application test with twenty people hydration increased by 76 percent over four weeks” is a statement you will not feel awkward about. “Moisturises by 76 percent” is already your own promise, and you are the one who will answer for it.
The difference is one line of text, and it costs a reputation. Regulators in many markets look closely at wording of this kind, and the complaint will not reach the Korean factory but whoever sells locally.