Table 1.

Psychometric validation parameters for the PSAAD diary

Parameter	Acceptability criteria	Actual
Test–retest reliability
Intraclass correlation coefficient	> 0.9 excellent, 0.7–0.9 acceptable, < 0.7 inadequate	0.81 (for a single measurement)
Internal consistency reliability
Cronbach coefficient alpha	≥ 0.70 acceptable	> 0.9 (every time point)
Corrected item-to-total correlations	≥ 0.40 acceptable	> 0.5 (every time point)
CID	–	0.63
Effect size, SD units	0.80 large, 0.5 medium, 0.2 small	0.28
CIR	–	1.03
Effect size, SD units	0.80 large, 0.5 medium, 0.2 small	0.45

CID clinically important difference, CIR clinically important response, PSAAD Pruritus and Symptoms Assessment for Atopic Dermatitis, SD standard deviation