The Pittsburgh Sleep Quality Index: Reliability, Factor Structure, and Related Clinical Factors among Children, Adolescents, and Young Adults with Chronic Pain
Table 2
Factor pattern matrix for the PSQI two-factor solution and factor matrix for the PSQI single-factor solution, comparing two extraction methods.
PSQI components
PCA extraction
ML extraction
PSQI two-factor solution
Factor 1
Factor 2
Factor 1
Factor 2
1. Subjective sleep quality
0.72
-0.21
0.81
0.01
2. Sleep latency
0.51
-0.25
0.44
0.16
3. Sleep duration
0.04
-0.87
0.23
0.54
4. Habitual sleep efficiency
-0.03
-0.91
-0.09
1.04
5. Sleep disturbances
0.74
0.06
0.59
-0.03
6. Use of sleeping medication
0.59
0.09
0.35
0.04
7. Daytime dysfunction
0.72
0.02
0.62
-0.08
% of total variance
41.07
15.96
21.38
24.49
Interfactor correlation
-0.35
0.47
PSQI single-factor solution
Factor 1
Factor 1
1. Subjective sleep quality
0.79
0.77
2. Sleep latency
0.63
0.55
3. Sleep duration
0.68
0.58
4. Habitual sleep efficiency
0.65
0.53
5. Sleep disturbances
0.61
0.54
6. Use of sleeping medication
0.46
0.37
7. Daytime dysfunction
0.62
0.55
% of total variance
41.07
31.95
Pittsburgh Sleep Quality Index, principal component analysis, and maximum likelihood. are in bold and were retained in the factor.
