Chuseok / Golden Week retention uplift vs paid spend efficiency

Festival retention uplift confounds paid efficiency reads. Korea.net Holidays documents Chuseok as a major Korean holiday; JNTO’s holiday calendar documents Japan’s Golden Week cluster. AppsFlyer’s retention and cohort analysis help defines how retention cohorts are built in that MMP — use it as the metric-definition page for this lab. Exact holiday dates must be taken from the calendar year you analyse.

Define the calculation

Compare D7 retention for a geo during the festival window with the same geo’s pre-festival baseline. Split organic-heavy versus paid install cohorts. Paid efficiency is read on paid-only ROAS or CPI→payer conversion, not on blended retention that includes holiday organic uplift.

Synthetic example

Baseline D7 retention 28.0%. Festival-window blended D7 34.0% (+6.0 pp). Paid-only festival D7 29.0% (+1.0 pp). If media reports “+6 pp retention from UA”, the synthetic split shows most uplift sits outside paid.

Evidence and limits

Holiday definitions come from Korea.net / JNTO. Retention definition is AppsFlyer’s cohort article. All percentages above are synthetic. No claim that Chuseok or Golden Week always lifts retention by 6 pp.

Download the evidence table.

Research checked 20 September 2026. Local draft; human editorial review pending. No CMS write performed.