Additional file 1 of Validation of a digital food frequency questionnaire for the Northern Sweden Diet Database

Supplementary material file 1: Table S1: List of 30 surveyed food groups and components included in each group. Table S2: Description of the evaluated diet indices and included components. The symbol “(+)” denotes healthy food groups, with increasing scores assigned to higher rank classes. The symbol “(-)” indicates inverse scoring where higher ranks receive lower scores. Table S3: Median daily intakes with 25 and 75 percentile limits in 30 food groups as estimated from the FFQ or the 24HDR in the validation group (n = 244) together with Spearman correlation coefficients and ratios between intakes assessed by the two recording methods. Table S4: Proportion (%) classified to food group tertiles (1, 2, 3) based on ranking of increasing intakes by the FFQ2020 (test method) and 24HDR (reference) recordings among the 244 participants with at least four 24HDR recordings. For food groups indicated in bold, italic text more than 50% of the participants had not eaten the product in any of the recorded 24HDR days. Table S5: Daily mean (sd) intakes of energy and 14 nutrients based on FFQ2020 and 24hDR recordings in the validation group (n = 244) and after exclusion of the lowest 5% and highest 1% based on PAL values (n = 231) together with Pearson and Spearman correlation coefficients for absolute and energy-adjusted (residual and energy density methods) data. Table S6: Proportion (%) of energy and nutrients in tertiles (1, 2, 3) based on a ranking of increasing intakes by the FFQ2020 and 24HDR recordings, respectively. Table S7: Central measures (variations) of food index scores and intake in the 30 surveyed foods groups and the repeatability of the estimated intakes as assessed by intraclass correlation coefficient with 95% CI using a two-way mixed-effects model, absolute agreement, and average measures. Table S8: Mean (sd) daily intake of energy and 14 nutrients as estimated from the baseline FFQ2020 and the follow-up FFQ2020, Pearson correlation coefficients, and intraclass correlation coefficient with 95% CI using a two-way mixed-effects model, absolute agreement, and average measures. Table S9: Spearman correlation coefficients in 30 food groups and 3 diet indexes as estimated from the FFQ or the 24HDR in the validation group for men (n = 95) and women (n = 149), respectively. Figure S1: Scatter plot for (A) PAL values estimated from 24HDRs versus FFQ2020 (the dotted lines represent lower cut-off, i.e., PAL 0.7), and (B) daily energy intake estimated from 24HDRs versus FFQ2020