Table 3.
Exploratory factor analysis of the 4-item questionnaire.
| Items in children (N=237) | Factor 1 | Factor 2 | Factor 3 | Uniqueness | Communality (1-uniqueness) % |
|---|---|---|---|---|---|
| Wake up time on weekdays | 0.8969 | 0.1547 | 84.5% | ||
| Bedtime on weekdays | 0.9590 | 0.0358 | 96.4% | ||
| Time spent in beda on weekdays | 0.9747 | 0.0061 | 99.4% | ||
| Wake up time on weekend days | -0.5989 | 0.5494 | 0.3073 | 69.3% | |
| Bedtime on weekend days | 0.8997 | 0.0998 | 90.0% | ||
| Time spent in beda on weekend days | 0.9662 | 0.0276 | 97.2% | ||
| Eigenvalue (proportion of variance) | 2.18 (0.36) | 2.02 (0.34) | 1.16 (0.19) | ||
| Explained varianceb | 0.895 or 89.5% | ||||
| Items in adolescents (N=258) | Factor 1 | Factor 2 | Uniqueness | Communality (1-uniqueness) % | |
| Wake up time on weekdays | 0.9023 | 10.0% | |||
| Bedtime on weekdays | 0.9936 | 0.0050 | 99.5% | ||
| Time spent in beda on weekdays | 0.9693 | 0.0456 | 95.4% | ||
| Wake up time on weekend days | -0.6211 | 0.6135 | 38.6% | ||
| Bedtime on weekend days | 0.9260 | 0.1242 | 87.6% | ||
| Time spent in beda on weekend days | 0.9676 | 0.0485 | 91.5% | ||
| Eigenvalue (proportion of variance) | 2.53 (0.42) | 1.73 (0.29) | |||
| Explained variancec | 0.710 or 71.0% |
SAYCARE: South American Youth Cardiovascular and Environmental study;
a
Based on the equation: (bedtime in clock time) - (wake up in clock time);
b
Proportion and explained variance for the first 3 factors (factor 1, factor 2 & factor 3) identified by using eigenvalue greater than one rule (Kaiser's rule);
c
Proportion and explained variance for the first 2 factors (factor 1 & factor 2) identified by using eigenvalue greater than one rule (Kaiser's rule).