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Ivan Ho1, Lauren Kennedy1, Bridget King1, Mary Ellen Prange1, Liza Boyar2, Julie Hodgson2, Irene Alfaro1, Ellis Lakhani3, Daniel Harrington2, Rachel Prowse3;
1Ontario Dietitians in Public Health, ON; 2Public Health Ontario, Toronto, ON; Memorial University of Newfoundland, St. John’s, NL

This project assessed the feasibility, reliability, and validity of online food costing for the 2019 National Nutritious Food Basket (NFB).

The NFB monitors the cost of healthy food in Canada, which is traditionally completed in-store. To maximize resources, increase reach, and adapt to COVID-19, we developed and tested an online protocol in Ontario.

In grocery chains with online platforms, the NFB was priced online in 12 stores to evaluate agreement in prices between raters (inter-rater reliability [IRR]) using percent perfect agreement and two-way random intra-class correlations (ICC) (n=572 pairs). Next, the NFB was priced in-store and online for 28 stores to estimate agreement between online and in-store prices (validity) using percent perfect agreement, paired t-tests and Pearson’s correlation for all (n=1708 pairs) and matched items (same product/brand and purchase unit) (n=1134).

NFB items were highly available online (97%); less than 1% were available in-store but not online. The protocol had good IRR (82% perfect agreement; ICC(2,1)=0.972, F=69.9, p<0.001). Across all items, 81% of in-store and online prices were identical. For matched items, 94% of prices were identical. The mean price difference (in-store minus online) of matched products was -1.8 cents (-0.005%). Regardless of whether items were matched, online and in-store prices were strongly correlated (all items: r=0.967, p<0.0001; matched items: r=0.993, p<0.0001) and did not significantly differ (all items: t=0.504, p=0.614; matched items: t=-1.338, p=0.181). IRR and validity were lower certain product categories (e.g. meat) and items (e.g. dinner rolls).

Online costing is a feasible, reliable and valid method to price the NFB in large grocery chains in Ontario. Minor protocol adjustments and rater training are expected to improve reliability and validity for problematic items.

The online protocol developed can be used as a framework for modernizing food affordability monitoring in other provinces and territories in Canada.

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