Step 1 (proposed ≤ ₹1.5 Cr)8-week randomised holdout, 20% per channel
Detectable lift≈ 1.3 pp (80% power, 5% level)
Step 2 (proposed ≤ ₹1.5 Cr)Fix data at source: payment_id, one PTP code, UTC, agent master
Step 3 (≥ ₹7 Cr)Deploy to the channel the test proves, by lift per rupee
Why not WhatsApp now?Most credit only because it sends the most messages; lift +0.07 pp
April strategy shiftDiD +1.3 pp, 95% CI −0.2 to +2.9: no detectable effect
Why not more agents?₹/agent-hour flat (₹16.1k–17.0k); contact shows no lift