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From |
"Nick Winter" <nwinter@policystudies.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: multiple response to binary |

Date |
Fri, 12 Jul 2002 13:01:53 -0400 |

Not sure this counts as "elegant", but if all your multiple case variables follow the pattern f*m*, then the following program should do it for you. Be sure to modify the list of stubs to be complete: *****************begin multcase.ado prog define multcase version 7 foreach stub in f4 f6 f8 { /* <==== ADD LIST OF STUBS */ vl `stub'* local varlist `r(varlist)' local nstub : word count `varlist' forval i=1/`nstub' { gen `stub'_val_`i' = . forval v=1/`nstub' { qui replace `stub'_val_`i' = 0 if `stub'm`v'!=. & `stub'_val_`i'==. qui replace `stub'_val_`i' = 1 if `stub'm`v'==`i' } } } end prog define vl, rclass syntax varlist return local varlist `varlist' end ***************end multcase.ado > -----Original Message----- > From: Lee Sieswerda [mailto:Lee.Sieswerda@tbdhu.com] > Sent: Friday, July 12, 2002 12:35 PM > To: Statalist (E-mail) > Subject: st: multiple response to binary > > > Hello all: > I have a data management problem (WinNT4, Stata v7). > > I have data from a questionnaire where some of the questions allow the > respondent to choose multiple responses. Lets say there 7 > possible responses > and they could choose any number of them. I would code this > as a set of 7 > binary variables. Unfortunately, the way it was coded was not so > straightforward. It was coded across 7 variables, but the > responses were > simply entered in the order in which they were given by the > respondent. So > the data look like this: > > f4m1 f4m2 f4m3 f4m4 f4m5 f4m6 f4m7 > 1 7 4 . . . . > 1 . . . . . . > 1 . . . . . . > 1 . . . . . . > 7 3 . . . . . > 1 . . . . . . > 1 2 3 4 . . . > 1 2 3 4 6 . . > 1 2 7 . . . . > 1 . . . . . . > > As you can see, you cannot simply tabulate the number of people who > responded 1, 2 , 3 etc because the responses are scattered over the 7 > variables in a different order for every person. The folks > who provided me > with this data use SPSS and they get around this problem by > using "multiple > responses sets". In SPSS, you can define a set of variables > as a multiple > response set (in this case, seven variables) and then ask for > tables of > frequencies and crosstabs generated from across the 7 > variables. It works, > but I'd much rather use Stata than SPSS. Also, the SPSS > solution is limited > to simple tables and doesn't permit you to get chi-square or other > statistics. > > Now, in Stata I know I can generate dummy variables from this > mess like > this: > gen dum1 = 0 > replace dum1 = 1 if f4m1==1 | f4m2==1 | f4m3==1 etc. > replace dum1 = . if f4m1==. & f4m2==. & f4m3==. etc. > gen dum2 = 0 > etc. > > However, this is tedious in the extreme and there are many of > these multiple > response questions in the dataset. I could automate the > procedure somewhat > using -foreach-, but its still more brute force than > elegance. Someone told > me about a SAS solution to this problem using an array procedure. Does > anyone have a nice elegant Stata solution to this problem? > > Thanks, > > Lee > > Lee Sieswerda, Epidemiologist > Thunder Bay District Health Unit > 999 Balmoral Street > Thunder Bay, Ontario > Canada P7B 6E7 > Tel: +1 (807) 625-5957 > Fax: +1 (807) 623-2369 > Lee.Sieswerda@tbdhu.com > www.tbdhu.com > > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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