Table 1

characteristics of the 6 sets of items
Item set
 n
 Population
 Total number of items
 Number of clinically relevant items
 Number of items after analysis
 Cronbach's alpha coefficient
 Number of latent roots > 1
 Variance explained by a single factor
A
 235
 Chronic pain
 88
 58
 39
 0.94
 3
 64%
B
 127
 Stroke
 21
 19
 14
 0.92
 1
 77%
C
 179
 RC + PD*
 80
 52
 32
 0.96
 2
 77%
D
 164
 RC + PD*
 80
 54
 41
 0.96
 2
 73%
E
 157
 RC + PD*
 80
 55
 43
 0.97
 3
 72%
F
 140
 RC + PD*
 80
 55
 36
 0.96
 3
 75%
All
 1002
170
 115
 78
 0.98
 5
 77%

n denotes the number of patients, who were presented with the item set

* RC denotes residents of supported housing, residential care or nursing homes

* PD denotes Parkinson's disease

Holman et al. Health and Quality of Life Outcomes 2005 3:83   doi:10.1186/1477-7525-3-83