SYS/COCKPIT
CRO tools
Pre-test, post-test reading and sequential peeking — the experimentation lab in one workspace.
Test duration
Turns a sample size into a calendar length. The rate is entered per day, week or month, and the duration is read in the unit you pick. A sample size without an end date is a test that will get peeked.
SYS/IN
SYS/OUT
Weeks
5.9
Other readings: 41 days · 1.3 months
Weekday and weekend traffic are not interchangeable. A month here is 365.25 / 12 days, not a named month.
Stopping before this n the moment p crosses α is peeking — the test is no longer fixed-horizon. Open the peeking tool.
| Rate | Duration |
|---|---|
| 100 | 23.4 |
| 200 | 11.7 |
| 400 | 5.9 |
| 800 | 3 |
| 1,600 | 1.6 |
Curve: n total ÷ rate, rounded up to a whole day, then converted into the unit you picked. The table is readable with JavaScript off.
How this is calculated
Method
Days = ceil(n_total / visitors_per_day). The rate can be entered per day, week or month: it is converted to a daily rate before the division (a week is 7 days, a month is 365.25 / 12). The display unit only changes the reading: weeks = days / 7, months = days / (365.25 / 12).
n_total = n per arm × number of arms, or the total n entered directly. This is calendar arithmetic, not a statistical model: the tool does not forecast traffic, it divides it.
Sources
The sample size itself comes from a two-proportion z-test — see Sample size (binary). This page only turns that n into weeks.
Limits
Traffic is not flat. A Wednesday is not a Saturday; a bank holiday is not a Tuesday. Round up to full weeks.
Stopping the moment p crosses α is peeking: the z-test assumes a horizon fixed in advance.