Table 5. Quality of evidence.
| Stage | Data sources | Evidence | Principal assumptions | Potential effects of bias on final estimates |
|---|---|---|---|---|
| All infectious intestinal disease | Population studies | Measured | Representivity of data | Moderate |
| Etiology | Population studies | Measured for most; inferred rarely | Accuracy and sensitivity of diagnostic methods | Moderate |
| Indigenous infection | National laboratory report surveillance; special studies | Measured | Completeness of reporting | Negligible |
| Foodborne transmission | National outbreak surveillance (GSURV)* | Measured for most; inferred rarely | Representivity of data | Major |
| Food attribution | GSURV | Measured | Representivity of data | Major |
| Presentations to primary care | Population studies | Measured | Representivity of data | Moderate |
| Hospitalizations | GSURV; special studies | Measured | Representivity of data | Moderate |
| Hospital occupancy | Hospital episode statistics | Measured | Representivity of data | Moderate |
| Deaths | GSURV | Measured | Representivity of data | Negligible |
| Food specific risks | National food survey | Measured | Representivity of data | Major |
*GSURV, National Surveillance Database for General Outbreaks of Infectious Intestinal Disease.