A user, Jan Lanke, found a bug in my -kornbrot- command.
I finally found the time, with the help of -pause-, to
find and fix the problem. The problem only occurred
when there were exact ties in the data across groups.
The fixed version appears below.
Rich Goldstein
*! kornbrot -- Kornbrot's rank difference test (STB-29: snp9)
program define kornbrot
version 4.0
local varlist "req ex max(1)"
local exp "req noprefix"
local if "opt"
local in "opt"
parse "`*'"
tempvar score rank ranka rankb touse id
if "`exp'" ~= "" {
unabbrev `exp'
}
preserve
quietly {
mark `touse' `if' `in'
markout `touse' `varlist' `exp'
drop if `touse'==0
}
quietly {
su `varlist'
local en _result(1)
gen `id'=_n
expand=2
gen `score'=`varlist'
replace `score'=`exp' if _n>`en'
egen `rank'=rank(`score')
replace `rank'=((2*`en')+1) - `rank'
gen `ranka'=`rank' if `varlist'==`score'
gen `rankb'=`rank' if `exp'==`score'
sort `id' `ranka'
replace `rankb'=`rankb'[_n+1] if `rankb'==.
drop if `ranka'==. | `ranka' == `ranka'[_n-1]
}
signrank `ranka'=`rankb'
end
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