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Natasha2018
Calcite | Level 5
If I have only aggregate data available for the 3 different age categories how do I calculate the 95% confidence interval for each of the age categories in SAS. Thanks for all help in advance
Eg:
Age cat. Numerator Denominator Proportion
10-19. 10 13325356. 0.00000075
20-29. 13 1446666. 0.00000968
30+ 60. 1231555. 0.00004872
6 REPLIES 6
Reeza
Super User

You can try PROC FREQ and use the N as your weights, you may need to reformat your data a bit to get exactly what you need. 

 

I think the first example is pretty close to your data structure.

 

You could also do the manual calculations in a data step assuming a binomial distribution.

 

 

PGStats
Opal | Level 21

This way:

 

data have;
input Agecat $ Numerator Denominator;
datalines;
10-19. 10 13325356
20-29. 13 1446666
30+ 60 1231555 
;

proc genmod data=have;
class agecat;
model numerator/denominator = agecat / dist=binomial;
lsmeans agecat / ilink cl;
run;

PG
PGStats
Opal | Level 21

Or you might just as well do:

 

data have;
input Agecat $ Numerator Denominator;
datalines;
10-19. 10 13325356
20-29. 13 1446666
30+ 60 1231555 
;

data limits;
set have;
BinomialLowerN = quantile("binomial", 0.025, numerator/denominator, denominator);
BinomialUpperN = quantile("binomial", 0.975, numerator/denominator, denominator);
run;

Note: with such large denominators, using the Poisson distribution would yield the same intervals.

 

PG
Natasha2018
Calcite | Level 5
Thanks for your help
I tried doing this but it yielded confidence intervals for the numerator and not the proportion.

Reeza
Super User

Your ratios are close to 0 so that the confidence intervals are pretty much 0 to 0. 

 

See this example:

 

data have;
input Agecat $ Type N ;
datalines;
10-19. 1 10 
10-19. 2 13325346 
20-29. 1 13 
20-29. 2 1446653
30+    1 60 
30+    2 1231495 
;

proc sort data=have;
by agecat;
run;


proc freq data=have;
by agecat;
table type / binomial ;
weight N;
run;

@Natasha2018 wrote:
Thanks for your help
I tried doing this but it yielded confidence intervals for the numerator and not the proportion.


 

PGStats
Opal | Level 21

proc genmod gave you the limits for the proportion in the Least Squares Means table under the Lower Mean and Upper Mean headings.

PG

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