st: bootstrap weighted mean

[Shuaizhang Feng <shuaizhang.feng@gmail.com>]

Dear list:

I was trying to bootstrap standard errors for the mean of two
variables. When I do so for simple means, i use the following ado
file.

program myratio, rclass
         summarize `1'
          local a1 = r(mean)
          summarize `2'
          local a2 = r(mean)
 return scalar ratio = `a1'/`a2'
end

and then do the following:

.bootstrap r(ratio), reps(100) saving(cratio, replace): myratio u1 u2, detail

and this gives the results as expected.

however, when i wanted to do ratio of weighted means, i modified the
ado file as follows:

program myratio_w, rclass
      summarize `1'[iw=`3']
          local a1 = r(mean)
      summarize `2'[iw=`3']
          local a2 = r(mean)
 return scalar ratio = `a1'/`a2'
end


and then use:

bootstrap r(ratio), reps(100) saving(cratio, replace): myratio_w u1 u2
weight, detail

then stata does not work properly and gives me the following message:

invalid syntax
an error occurred when bootstrap executed myratio_w
r(198);


I am wondering if anyone from the list can help me out. the difference
between the two ado files seem small Thanks in advance.

SZ
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