reaction was classified as: 0 = no redness; 1 = faint
redness; 2 = distinct redness; and 3 = extreme or maximum
redness. The photos were assessed by 10 independent
assessors who had no knowledge of the details
of the study and did not know the diagnoses. Each
assessor independently studied all photos in random
order on a computer screen. The final score for each
test subject was the average score of the 10 assessors.
Average inter-assessor reliability (expressed as the average
of the linear weighted kappa pairs) was 0.73,
good reliability, according to the criteria defined by
Landis and Koch (1977). The internal consistency of
the scale was very high, as indicated by its alpha
coefficient of 0.96.