Summary of covert observation data collected from each shop
| Baseline | Postintervention | ||
| 2 weeks | 6 weeks | ||
| Clearly displaying smaller portion meals available to all customers | Yes=2 No=6 | Yes=7 No=1 | Yes=6 No=2 |
| Smaller portion meals available to buy | Yes=6 No=2 | Yes=6 No=2 | Yes=8 No=0 |
| Active promotion of smaller portion meals | NA | Yes=5 No=3 | Yes=4 No=4 |
| Packaging used for regular meal | Boxes=7 Paper=1 | Boxes=8 | Boxes=8 |
| Weight of regular meal (g): battered fish | Mean=265.1 | Mean=277.9 | Mean=289.3 |
| Weight of regular meal (g): chips | Mean=399.9 | Mean=384.9 | Mean=339.1 |
| Weight of regular meal (g): total | Mean=665.0 | Mean=662.8 | Mean=628.4 |
| Packaging used for smaller portion meal | Boxes=6 | Boxes=6 | Boxes=8 |
| Weight of smaller portion meal (g): battered fish | Mean=175.7 | Mean=170.7 | Mean=174.0 |
| Weight of smaller portion meal (g): chips | Mean=273.0 | Mean=233.7 | Mean=247.4 |
| Weight of smaller portion meal (g): total | Mean=448.7 | Mean=404.3 | Mean=421.4 |
| Cost of regular meal (£) | Mean=£5.80 | Mean=£5.79 | Mean=£5.79 |
| Cost of smaller portion meal (£) | Mean=£4.22 | Mean=£4.07 | Mean=£4.00 |