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From |
"Sergiy Radyakin" <serjradyakin@gmail.com> |

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

Subject |
st: Extended missing codes for string variables??? |

Date |
Wed, 5 Nov 2008 12:50:22 -0500 |

Dear All, it has just occured to me that string variables do not have extended missing codes. A colleague of mine argues that this is perfectly fine, because: 1) one can use any text to stand for particular situations ("not applicable", "not responded",...) 2) for numerical values there are operations defined, which require that they yield missing values if any argument is missing. In a situation when I classify, say firms, by first letter of their name, I will have "Not applicable" and "No response" as instances in section "N", which is not what I want. Hence every time I deal with the strings like that is to specifically check for particular string values (and hence a different data entry operator inevitably chooses a different coding, the programs become highly oriented/dependent on a particular dataset), it is also quite tedious and annoying. One solution I see is to create a masking variable, which for each observation will have a code with an agreed upon code, e.g. 0=not applicable; 1= valid observation; 2=applicable, but refused to answer; 3=applicable, but respondent doesn't know; etc. I don't see this as a good solution, and I wonder, whether there is any technical possibility to instruct Stata that a particular string value should be treated as a missing value in some operations. I see it along the lines: char define make[extmiss_a] Not applicable char define make[extmiss_b] No response And later gen make_group=substr(make,1,1) will create empty values for those observations that had "Not applicable" or "No response" (however I still want to be able to distinguish between the two in some cases, like -tabulate-) What do you think about it? Are there extended missing string codes in other statistical packages? Thank you, Sergiy Radyakin * * 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/

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