A decision rule is a set of conditions that classify records. The rule predicts an outcome in the target field.
Viewing the decision rules helps you determine which conditions are likely to result in a specific outcome. For example, consider some hypothetical decision rules that could predict churn. These rules might identify classifications based on the ranges for customer age and number of previous claims. From these rules, you might observe that customers who have no or 1 claim and are older than 50 are more likely to churn.
The decision rule corresponds to a branch in a decision tree.