Table 3:
Common types of classification mistakes and examples
| Error Category | Example | Computed Class | Actual Class |
| Missed negation | not ready to quit smoking | Non-Tobacco | Tobacco |
| Verb tense confusion | has never tried to quit using tobacco | Non-Tobacco | Tobacco |
| Negation confusion | treatment not carried out due to patient smoking | Non-Tobacco | Tobacco |
| Missed negative verb | declined smoking cessation | Non-Tobacco | Tobacco |
| Missed negative adjective | ex-heavy cigarette smoker (20-39 per day) | Tobacco | Past-Tobacco |
| Missed “remission” context | severe tobacco dependence in remission | Tobacco | Past-Tobacco |
| Missed “history” context | history of prior cigarette smoking | Tobacco | Past-Tobacco |
| Missed “non-user” context | tobacco non-user | Tobacco | Non-Tobacco |
| Missed qualification | ready to quit smoking | Past-Tobacco | Tobacco |
| Missed negative adjective | tried unsuccessfully to quit smoking in the past | Past-Tobacco | Tobacco |
| Verb tense confusion | would like to quit tobacco use | Past-Tobacco | Tobacco |
| Unexplained | has reduced amount of tobacco smoked | Past-Tobacco | Tobacco |