interpurchase

Interpurchase is a term used in marketing and consumer analytics to describe the patterns and timing of purchases made by customers over time. Specifically, interpurchase time, also called interpurchase interval (IPI), refers to the duration between two consecutive purchases by the same customer or household. The concept is central to understanding purchasing cycles, forecasting demand, and designing retention strategies. The term is not uniformly standardized; many scholars prefer “interpurchase interval,” “purchase cycle,” or “recurrence interval,” depending on context.

Measurement and analysis: Interpurchase intervals are derived from transactional data with timestamps. Analysts compute the time difference between successive purchases for each customer, then summarize with averages, survival or hazard models, or distributional analyses. Short intervals indicate high purchasing frequency, while long intervals suggest dormancy. Models may account for seasonality, promotions, price shocks, and product category.

Applications: In retail analytics, interpurchase intervals inform inventory planning, promotion timing, and churn risk assessment. In subscription and e-commerce, stable IPIs indicate loyalty, while increasing IPIs may trigger re-engagement campaigns. Segmentation by interpurchase behavior helps tailor messaging and offers.

Limitations: Data sparsity, censored observations, and irregular purchase patterns complicate estimation. The metric should be complemented with recency, frequency, and monetary value (RFM) analyses.