Table 1.

Results of factor analysis and interitem correlation matrices for items included in the CBPI developed for owner assessment of chronic pain in dogs with osteoarthritis.

Factor	Item	Factor loading (r)*	Communality (h2)†	Item-total correlation (r)‡
Severity of pain (Cronbach’s α = 0.93)§	1 (Worst pain)	0.84	0.76	0.80
	2 (Least pain)	0.86	0.81	0.80
	3 (Average pain)	0.93	0.90	0.90
	4 (Current pain)	0.86	0.82	0.84
Interference with function (Cronbach’s α = 0.89)§	5 (General activity)	0.52	0.54	0.57
	6 (Enjoyment of life)	0.71	0.53	0.60
	7 (Ability to rise to standing)	0.78	0.67	0.71
	8 (Ability to walk)	0.72	0.67	0.72
	9 (Ability to run)	0.82	0.78	0.81
	10 (Ability to climb stairs)	0.84	0.78	0.80

For the total instrument, Cronbach’s α = 0.92.

^*Factor loading represents correlations between the items and factors. Loading values > 0.4 indicate that the item is highly correlated with the factor.¹¹,⁴³,⁴⁵,⁴⁷

^†Communality represents the proportion of the variance for each item that can be explained by the factor. When an item has a communality value < 0.40, it may not be related to the other items or there may be an additional factor that needs to be evaluated.²⁹,⁴³

^‡Item-total correlation represents correlations of each individual item with the total scale (with that item omitted). Items should have a correlation > 0.20 with the total score to be retained.¹¹,⁴⁵

^§Cronbach’s α measures the extent to which the item responses are highly correlated with each other; Cronbach’s α should be ≥ 0.70 for a set of items to be considered a scale.¹¹,⁴⁴,⁴⁶