| Subcategories | Definition | No (%) |
| Any provider factors | Among all reports, those having at least one provider factor present | 1786 (46) |
| Any classifiable provider factors | Among reports having provider factors, those having at least one provider factor that was classifiable at the broadest subcategory level or lower | 938 (53) |
| Types of provider factors | Among reports having at least one classifiable provider factor, types of factors present | |
| Skill-based errors | Actions unconsciously deviated from intentions due to execution failures | 485 (52) |
| Slip | Actions deviated from intentions due to inattention or inadvertent movement | 348 (37) |
| Lapse | Unconsciously forgetting something planned | 145 (15) |
| Ruled-based mistakes | Incorrect application of existing rules when solving a problem | 141 (15) |
| Application incorrect | Applying a rule that is valid but only under other circumstances | 23 (2.5) |
| Rule incorrect | Applying a rule that is never correct | 120 (13) |
| Knowledge-based mistakes | Incorrect application of knowledge when reasoning through a problem | 88 (9.4) |
| Incomplete knowledge | Inadequate knowledge of disease, treatment or resources available | 43 (4.6) |
| Reasoning error | Failure to focus attention on important issues, reluctance to relinquish interpretation despite conflicting information, overconfidence, biased interpretation and oversimplification | 51 (5.4) |
| Intentional violations | Conscious deviation from standard practice | 276 (29) |
| Routine | Provider was knowingly taking short-cuts (often due to time constraints or a culture of low expectations) | 66 (7.0) |
| Exceptional | Provider was forced to violate a rule to solve a problem or to avoid violating a more important rule | 207 (22) |
| Sabotage | Conscious violation with malicious intent | 3 (0.3) |
*Weighted to reflect incident reports for all patients discharged from the two hospitals.