Why can't I get a p-value smaller than 2.2e-16?

Question

I\'ve found this issue with t-tests and chi-squared in R but I assume this issue applies generally to other tests. If I do:

a <- 1:10
b <- 100:110
t.t         


        

Answer 1

Try something like this t.test(a,b)$p.value see if that gives you the accuracy you need. I believe it has more to do with the printing of the result than it does the actual stored computer value which should have the necessary precision.