Free tool · Test sizing
How long until you can read the test?
Not just the sample size: the weeks it takes to enroll it, let the metric mature and ship the change. Over about 10 weeks, a micro-tweak is the wrong test.
ReadyReadable within 6 weeks.
6 weeks to read
Run a standard A/B test with a guardrail metric, and decide the stopping rule before you start.
- Enrolling: 4.3 wk
- Metric maturing: 1.0 wk
- Launch lag: 0.0 wk
- Users per arm
- 850
- Users in total
- 1,700
- Readable in 6 weeks at your traffic
- A lift of about +18.4% or bigger.
Show as a table
| Lift | Weeks to read |
|---|---|
| +2% | 426 |
| +5% | 69 |
| +10% | 18 |
| +15% | 9 |
| +20% | 6 |
| +30% | 3 |
| +40% | 3 |
| +50% | 2 |
| +75% | 2 |
| +100% | 2 |
Two-sided test on a conversion rate, n = 16·p(1−p)/δ² scaled for your confidence and power (Kohavi et al.), at least 2 full weeks to cover weekly cycles. The same math the Gamify It MCP uses.
Your product has its own version of this.
Find the stage you're stuck in, then make one move. Connecting Gamify It is free; Pro starts it.