Table 7.
Updated sample size calculations for the adult outcomes using the between-cluster coefficient of variation from the baseline survey (with missing responses multiply imputed)
|
Outcome |
Baseline prevalence or mean (across all intervention and control clusters) |
Km |
Minimum detectable effect size |
Expected effect size in original study design |
|---|---|---|---|---|
| Adults | ||||
| Healthy eating |
37% of adults eating at least five portions of fruit and vegetables per day |
0.14 |
22% increase in prevalence |
50% increase in prevalence |
| Physical activity |
60% of adults doing at least five sessions of 30 min of moderate intensity physical activity per week |
0.14 |
19% increase in prevalence |
70% increase in prevalenceb |
| Mental health and wellbeing |
18% of adults reporting feeling anxious or depressed |
0.30 |
35% decrease in prevalence |
- |
| |
16% of adults reporting consulting their GP for emotional problems (anxiety and depression) in previous 12 months |
0.23 |
41% decrease in prevalence |
- |
| Mean Hope Scale score = 4.6 (range, 1 to 6, higher score indicates better mental wellbeing) | 0.03 | Increase of 0.2 standard deviations | - |
aEffect sizes for binary outcomes are relative increases in prevalence.
aCalculations are based on multiply imputed datasets; comparison to complete cases showed no substantial differences except in Km for adolescent fruit consumption which decreased from 0.05 to 0.004.
bBased on an expected baseline prevalence of 18%.