| Trend in reporting rates over time | No of reports to National Learning and Reporting System (NRLS) per month per hospital, provided by the National Patient Safety Agency (NPSA) |
| Relationship with type/severity of incidents reported | No of reports to NRLS per month per hospital categorised by incident type and severity, provided by the NPSA |
| Relationship with hospital size and characteristics | Healthcare Commission definitions of hospital type and size;20 data on patient age, gender, length of stay, and proportions of emergency and day-case admissions for 2004–2005, obtained from the Hospital Episodes Statistics website21 |