= Solution
Two distinct issues are:
* \b[Exposure measurement and comparability.] Infectious-dose estimates can have substantial error, and consumption categories may differ in infectivity or processing. If the assumed cohort exposure ratio is wrong, the expected allocation used in the <goodness-of-fit test> is wrong. The calendar distribution within the aggregated exposure period also matters for how many onsets have matured by the observation date.
* \b[Ascertainment of outcomes.] Clinical recognition, diagnostic testing, reporting and competing mortality may differ between cohorts. Unequal detection probabilities can alter the observed onset ratio even with equal biological susceptibility and <incubation periods>.
Thus the comparison must account for uncertainty in both its exposure denominator and its observed-disease numerator; a very small sampling <p-value> does not remove those model uncertainties.
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