TABLE 1.

Summary of psychometric evaluation

Property	Operational definition	Method used
Construct validity	Determines the validity of abstract variables that cannot be directly observed, such as pain. These constructs are assessed by their relationships with other variables (30)	Convergent and discriminant validity were assessed as two components of construct validity, as described below
Convergent validity	Evaluates how well items on a pain scale correlate with other measures of the same construct or related variables (30)	Calculated by correlating children’s NRS and CAS pain ratings for each pain level using two-tailed Pearson correlation coefficients. Spearman rank-order correlations were used to adjust for violations to normality
Discriminant validity	Evaluates how items on a pain scale correlate with other measures that are theoretically unrelated (30)	Calculated using Fisher’s Z-transformation to compare the magnitude of NRS-CAS correlations with the magnitude of NRS-FAS correlations
Interchangeability	The extent to which individual scores captured on one pain scale are transposable with the individual scores on another pain scale (ie, the quality of the intraindividual assessments)	Examined the absolute differences between individual participants’ NRS and CAS pain ratings as well as by using the Bland-Altman method (31)

CAS Coloured Analogue Scale; FAS Facial Affective Scale; NRS Numerical Rating Scale