Readmission - Rich Caruana etal On one of the pneumonia datasets, the rule-based system learned the rule “HasAsthama(x) ⇒ LowerRisk(x)”, i.e., that patients who have a history of asthma have lower risk of dying from pneumonia than the general population patients with a history of asthma usually were admitted not only to the hospital but directly to the ICU (Intensive Care Unit). [...] the aggressive care received by asthmatic patients was so effective that it lowered their risk of dying from pneumonia compared to the general population models trained on the data incorrectly learn that asthma lowers risk, when in fact asthmatics have much higher risk (if not hospitalized) The logistic regression model also learned that having asthma lowered risk, but this could easily be corrected by changing the weight on the asthma feature from negative to positive (or to zero).