Programming: combine two commands into one in order to bootstrap

[Sun Gno]

Hello all

I need to write my own STATA program that combines two commands into one, in order to bootstrap the value "Harrell's C statistic" I get from these commands.

These are my commands: 1) stcox age gender sex ecog 2) estat concordance

Here is what I have so far:
program define Cscore, rclass
stcox age gender sex ecog if ecog<3
estat concordance
return scalar tqm=r(mean)
end

I based the code I wrote from an example I found on this website under "Bootstrapping Results You've Calculated." https://www.ssc.wisc.edu/sscc/pubs/4-27.htm

The 4th line "return scalar tqm=r(mean)" is what is giving me trouble. The statistic I need is the output I get from estat concordance called the "Harrell's C." What exactly am I supposed to put in inside the parenthesis that says "mean"?

Thank you so much!

[Clyde Schechter]

If you check -help stcox postestimation- and follow the link to -estat concordance-, you will see that Harrel's C is returned in r(C).

[Sun Gno]

Thank you Dr. Schechter. I've changed it to r(c). But when I bootstrap per the website's directions I get the following results:

. program define Cscore, rclass
1. stcox age gender sex ecog if ecog<3
2. estat concordance
3. return scalar tqm=r(c)
4. end

. bootstrap tqm=r(tqm), reps(200) seed(12345): Cscore
(running Cscore1 on estimation sample)
'r(tqm)' evaluated to missing in full sample
r(322);

My question is:
-Should I change something in the fourth line of my program code (tqm?) What is "tqm=r(c)" supposed to mean?
-What does it mean when it says that r(tqm) has evaluated to missing in full sample?

[William Lisowski]

Perhaps the answer to your question posted on Stack Overflow will help resolve your problem.

http://stackoverflow.com/questions/3...-bootstrapping

Or, if what you typed was

return scalar tqm=r(c)

then do reread Clyde's post carefully, what you need is

return scalar tqm=r(C)

Stata is case-sensitive, c is not the same as C.

Your question about the meaning of "tqm=r(c)" on the return command is addressed by reading help return .

[Sun Gno]

I got it! Thank you all! the case sensitive suggestion did the trick.