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From |
"Joseph Coveney" <stajc2@gmail.com> |

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

Subject |
st: Re: Dealing with missing values |

Date |
Tue, 2 Apr 2013 09:21:00 +0900 |

Ching Wong wrote: I am currently using Stata 12. I need to convert the variable 'year' to a numeric variable by using the commands, gen yr = date(year, "Y"). However, there is 1 missing value generated. I have no idea why it would happen. As I have checked every single obs for 'year', there is no missing value. But when I checked the obs for 'yr', there is one "." after converting from 'year' to 'yr'. Why does it happen only for the year 1990 particularly, which is the maximum for the variable 'year'? And how should I deal with this missing value? I have tried to replace yr="" if yr==".". But it can't be eliminated. ie type mismatch r(109) Year Yr 1960 0 1940 -7305 1990 . <--?? 1986 9497 1915 -16436 -------------------------------------------------------------------------------- Just a couple of suggestions. Because Year is a string variable, it can take nonnumeric characters, some of which might not be readily discernable with some typefaces. So, make sure that the one in the "1990" observation is a numeral and not a lower-case el, and that the zero is a zero and not an upper-case oh. Data-entry errors do happen. You can scan for observations that aren't all numeric (that is, they contain at least one nonnumeric, nonwhite-space character) using the -real()- function, as in the line below. list Year if missing(real(Year)) If there's a single missing value in Yr and it's only for the year 1990, then you can replace it with the following. replace Yr = date("1990", "Y") taking care when typing-in "1990". It's a bit of a kludge, but you can think of it as a temporary workaround that will let you go on with your work while you figure out in parallel what's going wrong. Joseph Coveney P.S. It's always helpful to show exactly what you typed and exactly what you got, for example, a copy-and-paste from the Results window. Sometimes you believe that you typed something that you didn't, and it's easier for others to see the problem when you copy-and-paste the Results screen verbatim rather than paraphrase as you did. . input str4 Year Year 1. 1960 2. 1940 3. 1990 4. 1986 5. 1915 6. end . . generate float Yr = date(Year, "Y") . list, noobs +---------------+ | Year Yr | |---------------| | 1960 0 | | 1940 -7305 | | 1990 10958 | | 1986 9497 | | 1915 -16436 | +---------------+ * * 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/

**Follow-Ups**:**Re: st: Re: Dealing with missing values***From:*njcoxstata@gmail.com

**References**:**st: Dealing with missing values***From:*Ching Wong <ching.y.wong@student.adelaide.edu.au>

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