05 | RESEARCH-INFORMED ENROLMENT MODEL & CALIBRATION
Purpose: Develop a transparent, reproducible model for generating hypothetical loyalty-program enrolment probabilities using observed historical purchasing behaviour.
Method: Customer purchasing frequency and average order value are calculated from transactions preceding each monthly assessment (March–November 2011), using a 90-day historical window. Highly skewed variables are transformed using ln(1+x) and centred against observed March 2011 reference medians.
Scientific basis: Meyer-Waarden and Benavent (2009) and Leenheer et al. (2007) support the relationship between purchasing behaviour and loyalty-program self-selection. Singer and Willett (1993) provide methodological support for modelling event timing. Transferred behavioural coefficients are scenario assumptions, not directly estimated effects for this dataset.
Scenario design: Four behavioural scenarios (NO_EFFECT, WEAK, REFERENCE, STRONG) are combined with three hypothetical cumulative enrolment targets (5%, 15%, 30%). The targets are not observed or empirically established membership rates.
Calibration: Baseline log-hazard α is calibrated separately for all 12 combinations using numerical bisection. The calibration uses customer-specific cumulative relative exposure and targets an absolute enrolment-rate error of no more than 0.1 percentage points.
Validation: All 12 calibrated models passed the defined technical checks. Each model contains 3,974 eligible customers; probabilities remain within [0,1], and numerical calibration errors satisfy the specified tolerance.
Limitations: Successful calibration does not establish real-world predictive validity. Extreme purchasing behaviour can produce near-certain enrolment probabilities under stronger scenarios. Customers without eligible assessment periods require separate treatment. All loyalty-program outcomes remain hypothetical and cannot establish causal effects on purchasing behaviour.
Provenance: Historical transactions are observed UCI Online Retail data. Membership probabilities, behavioural-effect transfers, enrolment targets and calibration parameters are model-derived or assumed.