Prediction starts small. PA’s building block is the predictor variable, a single value measured for each individual. For example, recency, the number of weeks since the last time an individual made a purchase, committed a crime, or exhibited a medical symptom, often reveals the chances he or she will do it again in the near term. In many arenas, it makes sense to begin with the most recently active people first, whether for marketing contact, criminal investigation, or clinical assessment.
