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# Calcuating confidence interval (lower limit problem)

Hi everyone,

I am having problem calculating the lower limit of 99% confidence interval while I am calculating the age standardized rate.

Using below formula (which is one step before getting the CI), somehow it does not compute a value over 126,100.

l_lam99 = gaminv(1 - 0.99) / 2, ncases);

u_lam99 = gaminv(1 + 0.99) / 2, ncases);

For me the ncases are like 129,822 ~ 151,138, which is way higher than 126,100.

Is there any other way to calculate this right or any other solution please?

Thank you,

Albert

Posts: 2,655

## Re: Calcuating confidence interval (lower limit problem)

You may want to investigate the QUANTILE function.  In SAS 9.3, I had no trouble with the following:

l_lam99 = quantile('GAMMA', (1 - 0.99)/2, ncases);

and inserting 200,000 as the number of cases.

Good luck.

Steve Denham

New Contributor
Posts: 2

## Re: Calcuating confidence interval (lower limit problem)

Posted in reply to SteveDenham

Thank you so much Steve!

That worked on mine too. You've saved my days and hope you have a good week.

Cheers,

Albert Bang

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