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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