# Gem wager on a 7-day streak after a lesson: +14% day-7 retention

- Outcome: Won
- Page type: Retention (App)
- Test run by: [Duolingo](https://liftarchive.com/practitioners/duolingo/)
- Commentary by: LiftArchive (our analysis, not theirs)
- Original source: https://growth.design/case-studies/duolingo-user-retention
- Page: https://liftarchive.com/test/gd-duolingo-gem-streak-wager/

Duolingo added a step right after a lesson reward that invites learners to stake gems, its in-app currency, on keeping a 7-day streak, and day-7 retention rose 14%. Duolingo ran this; case study by Growth.Design, which walks through the step in its Duolingo user retention teardown.

## Result

**+14% day-7 retention**

- Day-7 retention: +14% with the wager step, as reported by Growth.Design. More learners were still active a week later.
- Growth.Design does not say whether the 14% is a relative lift or percentage points, so read it as a direction and rough size, not a precise figure.
- No other metrics are shared, such as gem spending, lesson counts or longer-term retention.

## Control

After finishing a lesson and getting the reward, the learner moved on through the normal lesson flow with no wager step.

## Variant

Right after the lesson reward, the learner sees an offer to bet gems that they will practice for 7 days in a row. In the Growth.Design walkthrough the stake is 50 gems.

## Why it likely won (our reading)

- The ask comes right after a reward, when the learner feels good and is most open to committing to more.
- Staking gems is a small investment. People tend to value and protect what they have put resources into, which is the sunk cost effect Growth.Design points to.
- The bet sets up a clear goal with a deadline, which gives the app a natural reason to remind the learner over the next days.
- The wager costs only virtual currency, so the downside of saying yes feels low, which likely keeps take-up high.

## Caveats

Growth.Design reports the figure without sample size, test length, confidence or a definition of the metric, so the size of the lift can't be checked. It covers a single app with a mature streak and currency system.

## How to run this test

- Hypothesis: If we offer users a chance to stake in-app currency on a 7-day streak right after they finish a session, then day-7 retention will rise because the stake and the clear goal give them a reason to come back each day.
- Primary metric: Day-7 retention
- Guardrail: Churn after a lost streak or lost wager
- Guardrail: Day-30 retention
- Guardrail: Paid conversion or purchases of in-app currency
- Who should test it: Habit apps with a daily use loop and an existing in-app currency or streak, such as language, fitness, meditation or study apps. It probably won't work in apps used a few times a month, or where there is no currency people care about losing.

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Credit: Duolingo ran this test and owns the result. Summary and commentary by LiftArchive (https://liftarchive.com/test/gd-duolingo-gem-streak-wager/).
Usage: Free to use, quote and build on, with credit and a link: name the practitioner or organization that ran the test and link to its LiftArchive page. The results belong to the practitioners who ran and shared them; the summaries and commentary are LiftArchive's.