← Casebook / CASE 02 · PREDICTIVE ANALYTICS

WORKED ANALYSIS / CASE 02 · PREDICTIVE ANALYTICS

A better churn model. But will it save anyone?

A decision-first churn model case covering AUC, decile lift, contact capacity, experimental uplift, retention economics and model-governance controls.

CASE 02 · PREDICTIVE ANALYTICS · FICTIONAL ORGANISATIONANALYSIS, NOT A CLAIM OF IMPLEMENTED IMPACT
EXECUTIVE ANSWER

Keep an interpretable baseline for a randomized retention pilot. A 0.009 AUC improvement is not proof of higher saved contribution, and predictive ranking does not establish treatment uplift.

0.009Synthetic AUC gap
68.2%Churners in top 30%
UnprovenIncremental retained customers

01 / THE MANAGEMENT PROBLEM

The wrong question was “which model scores higher?”

At fictional Contoso Play, a retention team wants to know whom to contact. The model team offers a logistic baseline and a gradient-boosting alternative. A buyer should care whether a contact saves more contribution than it costs—not whether the slide contains a more fashionable algorithm.

The management decision: which customers should receive which treatment, at what capacity and cost, based on demonstrable incremental retention?

Business sponsor

Retention / lifecycle marketing (proposed).

Risk owner

Model validation, data privacy and customer-treatment controls.

Baseline

3,000 held-out fictional subscribers; synthetic churn outcomes.

Missing outcome

No controlled treatment uplift, incremental margin or contactability measurement.

02 / THE DIAGNOSIS

The uplift in predictive ranking is only 0.009 AUC.

The gradient-boosting model scores 0.797 AUC, compared with 0.788 for logistic regression. That 0.009 gain is less than one AUC percentage point. Without paired uncertainty estimates, the case cannot assert that this difference is statistically robust.

Exhibit 1 · Discrimination and concentration

SYNTHETIC HOLDOUT
Logistic baseline0.788 AUC
Boosting model0.797 AUC
Churn events captured in top 30%68.2%
Horizontal scales show values out of 1.00; they are not incremental profit or treatment effectiveness. Synthetic deciles are derived from the existing exercise.
EvidenceObservationImplication
Model discrimination0.788 vs 0.797 AUCSmall offline performance difference
Top 10% of customers35.48% of churners; 3.55× liftRanking supports prioritization
Top 30% of customers68.2% of churnersCapacity constraint materially changes selection
Contact treatment outcomeNot presentNo evidence of causal uplift or ROI
Calibration / driftNot established in this caseDo not equate score with probability

Crucial distinction: predicting who will churn is not predicting who can be retained. Some high-risk customers will leave regardless of the offer; some lower-risk customers may be especially persuadable.

03 / THE OPTIONS

Keep the simplest adequate model until value is proved.

OptionTrade-offRecommendation
Deploy the boosting model immediatelyMarginal AUC gain; added governance cost; no uplift proofNo
Start with logistic ranking and controlled treatmentsInterpretable; easier operational baselineYes, for pilot
Send an offer to all flagged usersHigh cost, incentive leakage, contact fatigueReject
Do nothingAvoids costs but forfeits learningUse as randomized control, not a strategy for everyone

04 / THE INTERVENTION

Make treatment economics the unit of evaluation.

  1. 01 · SELECTDefine eligibility, contact capacity and channel permissions. Score eligible customers, then deduplicate and suppress ineligible contacts.
  2. 02 · RANDOMIZERandomly assign comparable customers to treatment and holdout. Keep the allocation rule and cohort fixed before launch.
  3. 03 · TREATProvide a documented offer through an approved channel; capture delivery, cost, acceptance, redemption and adverse experiences.
  4. 04 · MEASUREUse a predeclared retention window; compare treatment and holdout outcomes and contribution after incentive and servicing cost.
  5. 05 · ESCALATEMonitor complaints, fairness, consent, contact frequency, calibration and drift; let accountable humans pause campaigns.

05 / THE VALUE BRIDGE

Try the economics. Every assumption is editable.

This calculator uses the synthetic decile churn rates (the top three average 32.89%), extending into lower-ranked deciles when more people are selected. It is a scenario calculator, not a model result. The “prevented share” is an assumed treatment effect among otherwise-churning people reached, not an observed retention lift.

Exhibit 2 · Hypothetical campaign contribution

SCENARIO · NOT OBSERVED
Enter a scenario to calculate estimated net contribution.
Formula: expected churn events across selected synthetic deciles × reach × prevented share × (contribution − incentive) − selected × contact cost. Assumes stable churn risk across reachability and excludes taxes, fixed costs, discounting, heterogeneous treatment effects and uncertainty.

Break-even effect = campaign contact cost / (number reached × underlying risk × net contribution per saved customer). For scale approval, replace scenario assumptions with a randomized pilot estimate and confidence interval.

06 / DELIVERY PLAN

Six weeks to a falsifiable retention pilot.

  1. WEEK 01Business owner agrees retention definition, eligible population, channel budget, contribution assumptions and guardrails; model team verifies feature leakage.
  2. WEEK 02Risk and analytics validate holdout sampling, churn model stability, targeting fairness, contact permissions and treatment scripts.
  3. WEEKS 03–04Campaign operations runs the randomization, contact suppression, delivery and exception logging; independent monitoring tracks adverse outcomes.
  4. WEEKS 05–06Evaluate as much of the predeclared retention window as has elapsed. Do not call the pilot successful prematurely; continue measurement where required.

Kill / revise rule: stop scale-up if treatment-adjusted incremental contribution is nonpositive, complaints breach approved tolerances or confidence is insufficient to justify deployment. A positive AUC gap cannot override a failed business experiment.

07 / EVIDENCE LEDGER

Prediction is demonstrated. Retention impact is not.

ClaimClassification
AUC and decile captureObserved in synthetic holdout
Boosting model produces more net retention valueUnproved
Calculator contributionIllustrative assumptions only
Randomized pilot with a simple modelRecommended, not executed

Decision: do not buy model complexity until it clears the financial, statistical and operating thresholds. The first valuable capability is often a sound experiment.

Underlying synthetic churn report (PDF) ↗ · Original charts ↗