/**t Confidence Interval for the Mean **/
/***********************************************************
Macro tint1 does 1 sample t confidence interval for the Mean.
INPUT:
 dataset: input data set
 variable: variable to be analyzed
 level: confidence level
OUTPUT:
 sample mean and confidence interval
 sample std dev and confidence interval
***********************************************************/
%macro tint1(dataset,variable,level);
%let alpha2=%sysevalf(1-&level);
proc ttest data=&dataset sides=2 alpha=&alpha2;
 var &variable;
 ods select conflimits;
run;
%mend tint1;
/***********************************************************
Sample call: First submit the above macro code, then the code below.
This first part reads in the LDL data from class.
***********************************************************/
data ldl;
 input decrease_ldl @@;
 cards;
-7.6 13.9 27.1 14.8 6.3 42.0 41.7 18.5 31.2 24.0
;
run;
/***********************************************************
And this is how the macro is called to get a 95% confidence interval.
NOTE: This output also supplies a 95% confidence interval for the
population standard deviation, something we haven't studied.
***********************************************************/
%tint1(ldl,decrease_ldl,.95);