title 'Hot deck substitution of missing values in X within STRATUM'.
* Author: Th. van der Weegen .
* Katholieke Universiteit e-mail: T.vanderWeegen@maw.ru.nl .
* Date: 2006/03/24.
* READ DATA.
get file='c:\\program files\\spss\\Employee data.sav'.
* create some missing values.
IF RANGE(id,1,40) salary=0.
RENAME variables (id,jobcat,salary=respnr,stratum,x).
match files file=* /keep=respnr,stratum,x.
descriptives var=x.
* DATA PREPARATION.
recode x (missing=1)(else=0) into xnew.
recode x (missing=1)(else=0) into xmis.
compute seqnbeg=$casenum.
* necessary for reconstruction original sequence.
sort cases by stratum,xmis,seqnbeg.
compute #strat=lag(stratum).
if ($casenum=1 or #strat ne stratum) seqnstr=1.
compute #volg=lag(seqnstr).
do if (missing(seqnstr)).
+ compute seqnstr=#volg+1.
end if.
formats seqnbeg,seqnstr(f7.0).
* counting number of valid codes for x within stratum.
aggregate outfile='$hot.sav' /presorted /break=stratum /stratn=n(stratum)
/stratm=nmiss(x).
match files table='$hot.sav' /file=* /by stratum
/keep=respnr,stratum,x,seqnbeg,seqnstr,xnew,xmis,stratn,stratm.
* IF MISSING THEN RANDOM SEQUENCE NUMBER FROM STRATUM.
if (xmis=1) seqnstr=trunc(1+uniform(stratn-stratm)).
* SORTING SEQUENCENUMBERS.
sort cases by stratum,seqnstr,xnew.
do if (xnew=0).
+ compute xnew=x.
else if (seqnstr=lag(seqnstr) and stratum=lag(stratum)).
+ compute xnew=lag(xnew).
else.
+ compute xnew=$sysmis.
end if.
* SAVING RESULTS IN ORIGINAL SEQUENCE AND LABELING.
sort cases by seqnbeg.
compute x=xnew.
descriptives var=x.
save outfile='hotresult.sav' /keep=respnr,stratum,x.