Full_Name: Richard Mott Version: 1.9.0 OS: Windows XP Submission from: (NULL) (81.178.233.208) Shouldn't these give the same answer? > pchisq(67.60644,df=1,lower.tail=F,ncp=0) [1] 3.219647e-15 > pchisq(67.60644,df=1,lower.tail=F) [1] 1.996145e-16 >