Web-shop and store IAP in one LTV: a double-count diagnostic

A player who buys in the store and again in a web shop can appear twice in an LTV export if the join key is missing. This lab measures that risk on synthetic keys.

Define the calculation before using it

Enter store-IAP revenue, web-shop revenue, and revenue already identified as the same player-period after an authorised person key. The combined figure subtracts the overlap once.

Work through the synthetic example

4,000 store units and 2,500 web-shop units with 900 overlapping player-period revenue is 5,600 combined, not 6,500. If LTV used 6,500, payback looks easier than the cash.

Use the artifact and preserve its assumptions

Open the editable calculator to change the inputs and inspect the sensitivity view. The CSV records synthetic inputs and expected outputs; the JSON fixture keeps the equations available for reproduction. These calculations have been checked against the stated example. No measured campaign data is included.

The sensitivity rows vary only both by 20% below and above the entered value. They are scenarios, not confidence limits or a forecast distribution. A row outside the model’s constraints is labelled rather than turned into a plausible-looking result.

Evidence and limits

MMP event guides require unique event and customer identifiers for revenue. They do not automatically deduplicate store IAP against a separate web shop. See AppsFlyer in-app events, especially “In-app events”.

Person keys, tax treatment and refund timing differ by stack. This does not certify a web-shop MMP integration.

Background: Web shop attribution: measuring D2C without breaking your MMP setup and UA metrics explained: CPI, ROAS, LTV and payback. These existing articles provide context; the present calculation does not verify every archived claim.

Draft prepared 19 September 2026. Synthetic teaching example; human editorial and specialist review pending. No actual campaign outcome or recommended industry default is claimed.