Sequential test based on Evan Miller's

sequential-test.js

function sequentialTest(control, treatment, sample) {
    if (treatment - control >= 2.25 * Math.sqrt(sample)) {
        return 'treatment wins'
    } else if (control - treatment >= 2.25 * Math.sqrt(sample)) {
        return 'control wins'
    } else if (treatment + control >= sample) {
        return 'stop test. no winner'
    }
    return 'continue testing'
}