How to find the minimum range(start/end) which covers 95% of items in a numerical list?

Question

So its like saying 95% of the items sold in this website costs between $$25 - $150. While some items might cost less than $25 and other items might cost more than $150.

Is there a way to find this? Is this something related to CI - confidence Interval?

Answer 1

If you mean the narrowest range then something like this would do it

set.seed(1)
dat        <- rnorm(1000000)
ordereddat <- sort(dat)
width      <- ceiling(length(ordereddat) * 0.95)
difdat     <- diff(ordereddat, lag = width)
min        <- which(difdat == min(difdat)) 
c(ordereddat[min[1]] , ordereddat[min[1] + width])

producing

[1] -1.962899  1.961126

If you want as many items above as below then there is the simple but slightly wider

> c(quantile(dat, 0.025),  quantile(dat, 0.975))
     2.5%     97.5% 
-1.960232  1.964565