Table 1 |
|||||||
Summary of parameters used in the sample size calculation | |||||||
Outcome measures and mediators | Effect size | ICC used in sample size calculation | Standard deviation used in sample size calculation | Design effect | Number of clusters | Total subjects to be recruited | |
Before factoring in 30%attrition | After factoring in 30%attrition | ||||||
Calcium intake (milligrams per day) | 250 milligrams | 0.5* | 290 milligrams*** | 10.5 | 14.7 | 294 | 480 |
Physical activity duration (minutes per week) | 60 minutes | 0.05** | 150 minutes**** | 1.95 | 13 | 255 | 420 |
*Calculated using standard deviation from National Nutrition Survey 1998 and based on conservative estimates of inter- and intra-cluster variance [23].
**Based on estimates from published studies [30,31].
***Estimate from National Nutrition Survey 1998 [32].
****Based on estimates from published studies [33,34].
Tan et al.
Tan et al. BMC Public Health 2013 13:405 doi:10.1186/1471-2458-13-405