Revised-Goldberg method

Details of the method were described originally by Goldberg et al. [33], then revised by Black [18]. In brief, assuming that body weight is stable and EI equals EE [16], the revised-Goldberg method assesses the plausibility of rEI by comparing the ratio of rEI to BMR (rEI:BMR) to the ratio of EE to BMR (EE:BMR, also known as PAL) [18]. The method estimates 95% confidence limits of the agreement between rEI:BMR and PAL, with the following equation:

where PAL_value is the assigned PAL_value specified by the Institute of Medicine [34] for each group of PAL (PAL_value = 1.25, 1.50, 1.75 and 2.20 if sedentary, low active, active, and very active, respectively), CV_rEI is the intra-individual variation in rEI, d is the number of dietary assessments completed, CV_BMR is the intra-individual variation in repeated BMR measurements or the precision of estimated compared with measured BMR, and CV_PAL is inter-individual variation in PAL.

Based on suggestions from Black [18], the following values were used in the above equation: CV_BMR = 8.5%, CV_PAL = 15%. Since the present study used FFQ to assess dietary intake, the values for CV_rEI suggested by Tooze et al. [21] were used: CV_rEI = 19.8% for women and CV_rEI = 18.6% for men. Since only one FFQ was completed in the present study and the input variable for the cluster analysis was the average daily rEI, d was chosen to be equal to 1 [21, 35]. To account for the skewness in the distribution of energy intake, 95% confidence intervals for rEI:BMR were estimated on a logarithmic scale. Individuals with the natural log transformation of (rEI:BMR) below, above, and within the cut-off points were identified as EI-UR, EI-OR, and EI plausible reporters (EI-PR), respectively. The revised-Goldberg cut-offs used in this analysis were: lower = 0.75 and upper = 2.08 for sedentary, lower = 0.90 and upper = 2.49 for low active, lower = 1.05 and upper = 2.91 for active, and lower = 1.32 and upper = 3.65 for very active.