Purpose

Compare your case exposures to typical population exposures from Foodbook to prioritise hypotheses during outbreak investigations.

How references are computed

• References use Foodbook microdata with survey weights (as in OMD’s Stata workflow).
• If multiple PTs are selected, a single combined reference is computed across them.
• You can optionally limit the reference by Age Group (0-9, 10-19, 20-64, 65+) and Month.
• Defaults like "Canada" and "All" auto-deselect once you add other selections.

Analysis outputs

• Observed % : (Yes + Probably) / (Yes + Probably + No) in your cases.
• Reference % : Weighted population exposure % from Foodbook for your selected filters (rounded to 1 decimal).
• P-Value : Binomial test of observed vs reference % (upper tail).
• Classification : Alert (≤0.05), Borderline (≤0.10), Not Significant, or Insufficient Data.

Advanced (CEDARS upload)

• Upload the CEDARS Excel export. Expected sheets: ‘case exposure answer’ and ‘Salmonella Case’.
• Columns are auto-detected even if the wording changes (we normalise names).
• We analyse confirmed cases if available in the linelist sheet.

Good practice

• Interpret alongside lab, trace-back, and epi linkage evidence.
• Small totals can be unstable; look for patterns across multiple signals.
• Foodbook is de-identified open data; no direct identifiers are used.

Roadmap

• Optional Bayesian results to complement binomial tests (per OMD collaboration).