R clarification of the meaning of the formula

I have a code:

 x1=rnorm(100,-10,1)
 sum(x1>quantile(x1,0.05))/length(x1)
 

I would like to ask someone from the forum to explain to me what exactly the second line of code does. Thank you in advance for your help.

>Solution :

x1 is 100 normally distributed #s from a population with mean of -10.

quantile(x1,0.05) identifies the 5th percentile of that vector.

x1>quantile(x1,0.05) tests each element in x1 to see if it’s more than that 5th percentile, outputting TRUE (aka 1) if so, so its sum is a count of elements larger than the 5th percentile.

Finally, it’s divided by the number of elements in x1: 100. So we’re checking what percentage of the values are more than the 5th percentile. I’d expect 95%.

Leave a Reply