Usability numbers
usability_statsRead-only
Usability arithmetic with formulas shown. mode sus: score System Usability Scale responses (rows of ten 1-5 answers) with grade, percentile and 95% interval. mode discovery: participants needed to find a share of problems (Nielsen and Landauer). mode ab: sample size per variant for a conversion test (baseline, lift in percent, optional dailyVisitors). mode survey: responses needed for a margin of error.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| p | No | discovery: chance a participant hits a problem, default 0.31 | |
| lift | No | ab: smallest relative lift to detect, percent | |
| mode | No | Which calculator | |
| alpha | No | ab: significance level, 0.1, 0.05 or 0.01 | |
| power | No | ab: 0.8, 0.9 or 0.95 | |
| margin | No | survey: margin of error, e.g. 0.05 | |
| target | No | discovery: share of problems to find, default 0.85 | |
| baseline | No | ab: current conversion rate, e.g. 0.05 | |
| responses | No | sus: array of 10-number arrays | |
| confidence | No | survey: 0.9, 0.95 or 0.99 | |
| population | No | survey: total population, for the finite-population correction | |
| dailyVisitors | No | ab: traffic per day, to estimate how long to run |