Table 1 Results of statistical analyses of outcome data from RCTs that investigated food product labels
Outcome or subgroup | Independent comparisons | Total participants | Statistical method | Effect estimate: SMD (95% CI) | Test for overall effect or subgroup differences |
|---|---|---|---|---|---|
Product selection (with or without purchase) | 1 | 202 | SMD (IV, Random, 95% CI) | 0.31 (0.04 to 0.58) | N/A |
Product consumption | 5 | 680 | SMD (IV, Random, 95% CI) | 0.27 (−0.12 to 0.66)a | Z = 1.36, P = 0.17 |
- Intervention label denotes absence (“Fat-free) | 1 | 256 | SMD (IV, Random, 95% CI) | 0.42 (−0.08 to 0.91) | |
- Intervention label denotes absolute amount (“Low-fat”) | 4 | 424 | SMD (IV, Random, 95% CI) | 0.38 (−0.21 to 0.98)a | Chi2 = 5.15, df = 1, P = 0.02 |
- Female participants only | 2 | 343 | SMD (IV, Random, 95% CI) | 0.45 (−0.02 to 0.92)a | |
- Male and female participants | 3 | 337 | SMD (IV, Random, 95% CI) | 0.15 (−0.35 to 0.65)a | Chi2 = 0.75, df = 1, P = 0.39 |
- Parallel group (between-subjects) design | 3 | 344 | SMD (IV, Random, 95% CI) | 0.05 (−0.16 to 0.26)a | |
- Crossover (within-subjects) design | 2 | 336 | SMD (IV, Random, 95% CI) | 0.51 (0.29 to 0.72)a | Chi2 = 8.76, df = 1, P = 0.003 |
Intention to select or purchase product | 0 | 0 | N/A | Not estimable | N/A |
Intention to consume product | 0 | 0 | N/A | Not estimable | N/A |
Belief associated with product consumption | 1 | 34 | SMD (IV, Random, 95% CI) | −0.66 (−1.32 to 0.00) | N/A |
1 | 34 | SMD (IV, Random, 95% CI) | −0.14 (−0.79 to 0.51) | N/A | |
Product appeal | 8 | 1013 | SMD (IV, Random, 95% CI) | −0.01 (−0.14 to 0.13)a | Z = 0.09, P = 0.93. |
- Intervention label denotes absence (“Fat-free) | 2 | 412 | SMD (IV, Random, 95% CI) | −0.01 (−0.21 to 0.18)a | |
- Intervention label denotes absolute amount (“Low-fat”) | 2 | 167 | SMD (IV, Random, 95% CI) | −0.09 (−0.28 to 0.11)a | |
- Intervention label denotes relative amount (“Reduced-fat) | 4 | 434 | SMD (IV, Random, 95% CI) | 0.03 (−0.19 to 0.26)a | Chi2 = 0.23, df = 2, P = 0.89 |
- Female participants only | 2 | 343 | SMD (IV, Random, 95% CI) | 0.09 (−0.12 to 0.30)a | |
- Male and female participants | 6 | 670 | SMD (IV, Random, 95% CI) | −0.06 (−0.24 to 0.12)a | Chi2 = 1.10, df = 1, P = 0.30 |
- Parallel group (between-subjects) design | 4 | 301 | SMD (IV, Random, 95% CI) | 0.00 (−0.22 to 0.23)a | |
- Crossover (within-subjects) design | 4 | 712 | SMD (IV, Random, 95% CI) | −0.03 (−0.23 to 0.17)a | Chi2 = 0.04, df = 1, P = 0.84 |
Understanding of label | 3 | 155 | SMD (IV, Random, 95% CI) | −0.57 (−0.89 to −0.26)a | Z = 3.57, P = 0.0004 |