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| From | Steve Nakoneshny <scnakone@ucalgary.ca> |
| To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
| Subject | Re: st: Creating Dummys from a variable with 5 categories |
| Date | Sun, 2 Dec 2012 10:02:51 -0700 |
As an alternate approach, might it not make sense to create a series of indicators using -tab foo, g(bar)-? Steve Sent via carrier pigeon On 2012-12-02, at 9:50 AM, "Nick Cox" <njcoxstata@gmail.com> wrote: > As Daniel Klein's posting also indicated, this procedure is a little > risky and may give incorrect results if you have missing values. > Usually you want missing values to be reflected by missing values in > the indicator. > > A more general definition, which allows a one-line Stata solution, is > > gen <dummy> = cond(missing(<varname>), ., <expression>) > > when you want the <dummy> to be 1 if <expression> is true and 0 if it is false. > > For example > > gen flatfee = cond(missing(myvar), ., myvar == 1) > > gen nonflatfee = cond(missing(myvar), ., myvar == 0) > > As said, you may know that you want missing values to imply 1 or 0 for > your indicator, in which case you can supply the appropriate answer in > place of . (system missing). > > Here and elsewhere, I recommend the term "indicator" over "dummy". I > have heard too many stories in which "dummy" was misinterpreted as > implying disparagement, insult or offence, but no such stories about > "indicator". > > Nick > > On Sun, Dec 2, 2012 at 3:53 PM, JVerkuilen (Gmail) > <jvverkuilen@gmail.com> wrote: >> Your question isn't quite specified to be answerable but here's a >> quick way to make a dummy variable that has value 1 for flat fee and 0 >> for any other value of myvar: >> >> generate flatfee = 1 >> replace flatfee = 0 if myvar != 1 >> >> What this syntax does is (a) make a variable flatfee that has 1 >> everywhere and (b) change all values for which myvar does not indicate >> a flat fee to 0. You could also >> >> generate flatfee = 0 >> replace flatfee = 1 if myvar = 1 >> >> which is the opposite process, as it changes the 0s to 1s where flat >> fee is applicable. This seems more natural than coding flat fee the 0 >> and all other methods 1, but if you want the other way around >> >> generate nonflatfee = 1 - flatfee >> >> Try these and then check your work by >> >> tabulate flatfee myvar >> >> which is always a good idea whenever you're recoding variables. You >> should see a 2x5 table that has the counts all in the right place. >> >> >> On Sun, Dec 2, 2012 at 3:27 AM, Sharon Brody <brodysharon@yahoo.co.uk> wrote: > >>> I have a variable with 5 answers and need to make a dummy variable from it >>> >>> The question asked - How are you charged for your waste: >>> 1. Flat Fee >>> 2. Weight or Volume >>> 3. Frequency >>> 4. Not Charged >>> 5. Dont Know >>> >>> If I want to create a dummy variable that uses Flat Fee as a reference point >>> >>> 1. How do I create a dummy (I have tried the basic way - gen XXXX =1 replace XXXX=0 if YYYY=>2) but I believe this is incorrect as it doesnt incorporate all the variables. >>> >>> 2. How do I get Stata 12 to use "Flat Fee" as the reference base point >>> > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/