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From |
daniel klein <klein.daniel.81@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Confirming whether a variable is binary or continuous |

Date |
Fri, 16 Mar 2012 23:28:24 +0100 |

Bert, as you already realized, there is no possibility to tell whether a variable is intended to be a binary indicator or merely happens to only have values 0 and 1. For this purpose you will need more information on that variable. An option, indicating continuous variables, seems to be a good idea. However, I would like to add some thoughts here. Checking for binary variables -tabulate- is useful but the information in r(r) is not all it has to offer. Note that a variable with values 1 and 2 will also result in r(r) = 2 and therfore will be declared a binary variable by your program. Here is how I checked for binary variables in one of my programs using -tabulate- with -matrow()- option [...] tempname M qui ta <var> ,matrow(`M') if (r(r) != 2) | (`M'[1, 1] != 0) | (`M'[2, 1] != 1) { di "<var> is not a binary variable" } [...] You will have to make sure <var> is not a string variable, as it is not allowed to use option -matrow()- with string variables. If you do not want to check, you can use -levelsof- to get the values of any variable. In any case, user-written software is not required here (although the first versions of -levelsof- were, at least partly, user-written by Nick Cox, as far as I know). I would not use -compress- as it is, in general, a bad idea to make (any) changes to the user's dataset if these changes are not the very purpose of your program. You could use -preserve- to avoid permanent changes but my guess is your program will execute faster if you just use -tabulate- (as shown above) in a loop for all numeric variables (not declared "continuous" by the user). Best Daniel * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Confirming whether a variable is binary or continuous***From:*Nick Cox <njcoxstata@gmail.com>

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