FAQ - Answer 2 (C)

The protocol used was as described in the ISBS conference poster. Its aim was to assess measurement uncertainties associated with rapid TEWL measurement. To this end, skin-related uncertainties were reduced by confining the study to a single test area of a single volunteer in a single session. The measurements were performed on seven test sites marked on the left volar forearm of an elderly volunteer, as illustrated in the photo below

Note that the two instruments were not tested in the same session. Therefore, neither the skin properties nor the exact location of each site are directly comparable. What is at issue here is repeatability, ie the ability of each instrument to come up with the same reading when the same reading is expected. This repeatability property is measured by the error bars (±1 standard deviation) in the above figure.