Hi ALLSTATers,
I am trying to calculate the approx 95% confidence intervals for the
standardised incidence rate of certain cancers using Byars approximation.
I have a spreadsheet set up in Excel to calculate this manually. The
formula to calculate it, as set up in Excel, contains the following:
CHIINV(0.025,2*AQ7+2)
where AQ7 represents the sample size.
Now for most sample sizes this works fine, however for certain sample sizes
(for example 409)the calculation returns the answer #NUM.
Has anybody else come across this in the past, and if so, how is it
bypassed.
Thanks in advance,
Christopher D Fergusson
Trent Cancer Registry
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