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Table 4 Results of primary outcome analysis by site per day (log total calories)

From: Impact of reducing portion sizes in worksite cafeterias: a stepped wedge randomised controlled pilot trial

Analysis

Variable

Coefficients (95% CIs)a

Percentage change (%) (95% CIs) a

pa

Change in energy purchased (kcal)b

Mean number of transactions (s.d.)b

Change in energy purchased (kcal) per transactionb

Overall

Portion size intervention period

−0.093 (− 0.182, − 0.004)

−8.92 (− 16.68, − 0.44)

0.081

−10,208

537 (342)

−19.0

By site

Portion size intervention period

Site 1

−0.116 (− 0.271, 0.039)

− 10.94 (− 23.74, 4.01)

0.188

−12,541

460 (80)

−27.3

Site 2

−0.052 (− 0.194, 0.090)

−5.05 (− 17.61, 9.44)

0.499

− 11,738

877 (129)

− 13.4

Site 3

−0.003 (− 0.141, 0.134)

−0.32 (− 13.13, 14.38)

0.965

−2010

340 (28)

− 5.9

Site 4

−0.074 (− 0.212, 0.064)

−7.13 (− 19.07, 6.56)

0.328

−15,575

1054 (233)

−14.8

Site 5

−0.150 (− 0.288, − 0.012)

−13.96 (− 25.04, − 1.24)

0.071

− 10,034

338 (25)

−29.7

Site 6

−0.170 (− 0.311, − 0.029)

−15.63 (− 26.74, − 2.84)

0.051

− 4468

147 (45)

−30.4

  1. a As the p-values (the more robust Kenward-Roger adjusted) and CIs (Wald) presented here have been calculated using different assumptions, there is not always an equivalence of interpretation between the 95% confidence intervals and significant p-values. b Based on raw data