Table 5

Repeatability of the EPIC physical activity questionnaire over 10 months

EPIC questionnaire measure

Mean (SD) difference^a

Correlation (ρ)

95% CI

Continuous measure (MET hours/week)

Total non-occupational activity

-0.6 (59.0)

0.65

0.55, 0.72

Recreational activity

0.7 (47.7)

0.58

0.48, 0.67

Household activity

-1.3 (33.5)

0.73

0.66, 0.79

Vigorous activity, self-rated^b

3.3 (34.7)

0.63

0.54, 0.72

Vigorous activity, MET-assigned^b

1.5 (32.4)

0.71

0.63, 0.78

Light-moderate activity^c

-2.15 (51.0)

0.67

0.58, 0.74

Categorical measure

K_w

Total physical activity index

0.62

0.53, 0.71

Cambridge physical activity index

0.66

0.58, 0.74

P < 0.0001 for all measures.

EPIC, European Prospective Investigation into Cancer and Nutrition; ρ, Spearman rank correlation coefficient; CI, confidence interval; K_w weighted kappa

^a Mean (SD) difference in MET-hours/week: EPIC 10-month minus baseline questionnaire.

^b Vigorous activity was estimated (1) in a separate question about time in activities causing sweating or faster heartbeat, (2) using the sum of time spent in activities with MET values ≥ 6

^c Light-moderate activity was estimated using the sum of time spent in activities with MET values < 6

Cust et al. International Journal of Behavioral Nutrition and Physical Activity 2008 5:33   doi:10.1186/1479-5868-5-33