We're running Apple One bundle upsell campaigns across email, in-app, and paid social. Which channel is actually driving the upgrades?
This is a case where multi-touch attribution breaks down because all three channels are touching the same users in quick succession. I used a Shapley value decomposition to fairly allocate credit, plus a channel-holdout experiment from last month to validate.
True incremental contribution:
In-app notifications: 52% of incremental upgrades
These reach users at the moment they're already engaged with an Apple service (watching Apple TV+, listening on Apple Music). The timing creates a natural upsell moment. Holdout test showed removing in-app notifications reduced upgrades by 48% — closely matching the Shapley estimate.
Email campaigns: 31% of incremental upgrades
Email functions as the consideration nudge. Users who received the "You're paying $32/month for 3 services — Apple One is $19.95" comparison email were 2.4x more likely to upgrade within 7 days. But — critically — email alone without in-app follow-up only converts at 1.2%, vs. 4.8% when both touch the user.
Paid social (Meta/Instagram): 17% of incremental upgrades
Social is the awareness layer for non-engaged users — people who subscribe to one Apple service but rarely open it. Without social, these users would never encounter the bundle pitch. However, social's CPA ($89/upgrade) is 3x higher than email ($28) and 5x higher than in-app ($17).
The interaction effect matters most:
The sequence in-app notification followed by email within 48 hours converts at 6.3%, which is higher than either channel alone or any other ordering. I'd structure the campaign cadence around that sequence and use paid social only for the dormant subscriber segment that in-app can't reach.
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Results are based on causal inference models applied to your campaign data. Always verify critical decisions with your team.