Эд Кайл у себя на сайте поменял формулу оценки надежности РН и добавил доверительный интервал.
http://www.spacelaunchreport.com/log2018.html#rate
Цитировать* Lewis Point Estimate Determined as Follows.
Maximum Liklihood Estimate (MLE)= x/n
where x=success, n=tries
For MLE<=0.5, use Wilson Method = (x+2)/(n+4)
For MLE Between 0.5 and 0.9, use MLE = x/n
For MLE>=0.9, use Laplace Method = (x+1)/(n+2)
Lewis, J. & Lauro, J., "Improving the Accuracy of Small-Sample
Estimates of Completion Rates", Journal of Usability Studies,
Issue 3, Vol. 1, May 2006, pp. 136-150.
* Adjusted-Wald 95% Confidence Interval Range Determined
as Follows.
Pw = (x+1.920 8) /(n+3.8416)
CI = Pw +/- 1.96*sqrt[(Pw*(1-Pw))/(n+3.8416)]
(maximum range 1.00)
Раньше было просто (x + 1) / (n + 2)