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st: check whether a variable has any missing values


From   Jacob Wegelin <jacob.wegelin@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: check whether a variable has any missing values
Date   Sat, 28 Mar 2009 14:57:27 -0400

The following program checks whether a variable contains any missing
values. This seems an awkward way to do it. Does a more elegant
approach exist? I haven't found an extended macro function that takes
care of this, and the function -missing()- does not do the trick.

clear all
capture program drop checkIfAnyMissing
program define checkIfAnyMissing, rclass
   return local variable="`1'"
   qui tabulate `1'
   local howManyObs=`r(N)'
   qui tabulate `1', missing
   local howManyRowInclMissing=`r(N)'
   if (`howManyObs'== `howManyRowInclMissing') {
      return local answer="`1' has no missing values"
      return scalar missing=0
      }
   else {
      return local answer="`1' has at least one missing value"
      return scalar missing=1
      }
end

input bad good str8 strbad str8 strgood
0 0 0 0
. 1 "" 1
end

list

di missing(bad)

di missing(good)

checkIfAnyMissing bad
return list


checkIfAnyMissing good
return list


checkIfAnyMissing strbad
return list


checkIfAnyMissing strgood
return list

Thanks for any tips

Jacob Wegelin
Assistant Professor
Department of Biostatistics
Virginia Commonwealth University
730 East Broad Street Room 3006
P. O. Box 980032
Richmond VA 23298-0032
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