y=13 ; n=46021 # input data alpha=0.05 # sets a 95% interval v1=2*y ; v2=2*(y+1) # get df. CL=qchisq(alpha/2,v1)/2 CU=qchisq(1-alpha/2,v2)/2 CL # lower conf. limit CU # upper conf. limit # express as rates / 100000 CL*100000/n # lower conf. limit CU*100000/n # upper conf. limit

> CL # lower conf. limit [1] 6.921952 > CU # upper conf. limit [1] 22.23040 > > # express as rates / 100000 > CL*100000/n # lower conf. limit [1] 15.04086 > CU*100000/n # upper conf. limit [1] 48.3049