Table 2.

Sources of variation in health-related quality-of-life ratings estimated from a two-facet fully-crossed design, according to health state (n = 183)

Source of variation	Estimated variance component	Percent of total variability
Current health state
Person	0.205	34.3
Rater	0.039	6.5
Occasion	0.000^a	0.0
Person x Rater	0.100	16.8
Person x Occasion	0.029	4.8
Rater x Occasion	0.000^a	0.0
Residual	0.224	37.6
Mild to moderate stroke
Person	0.133	20.4
Rater	0.007	1.1
Occasion	0.004	0.7
Person x Rater	0.089	13.7
Person x Occasion	0.001	0.2
Rater x Occasion	0.000^a	0.0
Residual	0.418	64.0
Incurable brain cancer
Person	0.067	16.4
Rater	0.000^a	0.0
Occasion	0.000^a	0.1
Person x Rater	0.066	15.9
Person x Occasion	0.000^a	0.0
Rater x Occasion	0.000^a	0.1
Residual	0.277	67.5
Severe dementia
Person	0.025	11.1
Rater	0.000^a	0.0
Occasion	0.000^a	0.0
Person x Rater	0.049	21.3
Person x Occasion	0.000^a	0.0
Rater x Occasion	0.003	1.2
Residual	0.152	66.5

^aNegative variances set to zero as recommended by Cronbach et al. [25]