Difference in two medians and 95% CI

[Celene Yap]

I saw a post using bootstrap to calculate the 95% CI for the difference of two medians and tried to run the command in the Do-File_Editor with the following information:
/* Define a program to return medians */
program define qq, rclass
centile TimeSedation if StudyArm==1
scalar m1 = r(c_1)
centile TimeSedation if StudyArm==2
scalar m2 = r(c_1)
centile TimeSedation if StudyArm==3
scalar m3 = r(c_1)
#delim;
bootstrap
m1 = r(m1)
m2 = r(m2)
m3 = r(m3)
d12 = (r(m1)-r(m2))
d32 = (r(m3)-r(m2))
DID = (r(m3)-2*r(m2)+r(m1)),
ties strata(StudyArm) rep(1000) nodots saving(bs01, replace): qq;
#delim cr
estat bootstrap

It works the first time but when I tried to re-run it again, it returned with the following message:

. /* Define a program to return medians */
. program define qq, rclass
1. centile TimeSedation if StudyArm==1
2. scalar m1 = r(c_1)
3. centile TimeSedation if StudyArm==2
4. scalar m2 = r(c_1)
5. centile TimeSedation if StudyArm==3
6. scalar m3 = r(c_1)
7. #delim;
delimiter now ;
. bootstrap
> m1 = r(m1)
> m2 = r(m2)
> m3 = r(m3)
> d12 = (r(m1)-r(m2))
> d32 = (r(m3)-r(m2))
> DID = (r(m3)-2*r(m2)+r(m1)),
> ties strata(StudyArm) rep(1000) nodots saving(bs01, replace): qq;
8. #delim cr
delimiter now cr
. estat bootstrap
9.
unexpected end of file
r(612);

end of do-file

r(612);

Any ideas how to fix it? Or any advice on getting the 95% CI?

Thanks!

[Nick Cox]

You never say when the program ends. You need an

end

statement. See the help for program.

I guess this is closer to what you want.

program define qq, rclass
    centile TimeSedation if StudyArm==1
    return scalar m1 = r(c_1)
    centile TimeSedation if StudyArm==2
    return scalar m2 = r(c_1)
    centile TimeSedation if StudyArm==3
    return scalar m3 = r(c_1)
end

bootstrap m1 = r(m1) m2 = r(m2)  m3 = r(m3) ///
d12 = (r(m1)-r(m2)) d32 = (r(m3)-r(m2)) DID = (r(m3)-2*r(m2)+r(m1)), ///
ties strata(StudyArm) rep(1000) nodots saving(bs01, replace): qq;

estat bootstrap

[Celene Yap]

Thanks Nick for your reply but it returned with different error messages as I tried to use the code you suggested. Did I miss anything this time? I pasted the code on the Do-file editor.


. program define qq, rclass
1. centile TimeSedation if StudyArm==1
2. return scalar m1 = r(c_1)
3. centile TimeSedation if StudyArm==2
4. return scalar m2 = r(c_1)
5. centile TimeSedation if StudyArm==3
6. return scalar m3 = r(c_1)
7. end

.
. bootstrap m1 = r(m1) m2 = r(m2) m3 = r(m3) ///
> d12 = (r(m1)-r(m2)) d32 = (r(m3)-r(m2)) DID = (r(m3)-2*r(m2)+r(m1)), ///
> ties strata(StudyArm) rep(1000) nodots saving(bs01, replace): qq;
qq; command not found
r(111);

end of do-file

r(111);



. program define qq, rclass

. do "C:\Users\celeney\AppData\Local\Temp\STD01000000.t mp"

. centile TimeSedation if StudyArm==1

-- Binom. Interp. --
Variable | Obs Percentile Centile [95% Conf. Interval]
-------------+-------------------------------------------------------------
TimeSedation | 111 50 11 8.656538 15

. return scalar m1 = r(c_1)
non r-class program may not set r()
r(151);

end of do-file

r(151);