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From |
joe j <joe.stata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: AW: egen(mean or suchlike) for a string variable |

Date |
Fri, 9 Oct 2009 17:34:40 +0200 |

Thank you Martin and Nick for the suggestions. much much appreciated. I'd look at your references. JJ On Fri, Oct 9, 2009 at 4:49 PM, Nick Cox <n.j.cox@durham.ac.uk> wrote: > You should check for different spellings etc. Spellings could be inconsistencies in use of upper and lower case, extra leading, internal, or trailing spaces etc. > > See http://www.stata.com/support/faqs/data/diff.html for some technique for identifying inconsistencies. > > Nick > n.j.cox@durham.ac.uk > > joe j > > Thank you, Nick, for complimenting Martin's advice. I do find a slight > difference in outcomes from the two procedures (may be about 0.1% in a > sample of close to a million, so I can't immediately tell why this is > so; perhaps due to the complications you allude). Good to know also > about -egen, mode()- > > On Thu, Oct 8, 2009 at 6:23 PM, Nick Cox <n.j.cox@durham.ac.uk> wrote: >> Let's underline that this can all be done with strings. There is no need to resort to -encode- or otherwise to convert to numeric. >> >> Missing, i.e. empty, strings sort first. Thus after -input- and -trim()-, Martin's code can be slimmed to >> >> bys year Prof (Uni) : replace Uni = Uni[_N] if missing(Uni) >> >> -- without any need for an extra variable. >> >> However, there is no check here for different non-missing values within groups of -year Prof-. >> >> In the same territory, note that -egen, mode()- takes string arguments as well as numeric, so can be used for imputation. However, the direct route that Martin exemplifies has many advantages. >> >> Nick >> n.j.cox@durham.ac.uk >> >> Martin Weiss >> >> ************* >> clear* >> >> inp year str10(Uni Prof) >> 1990 Harvard " S Smith" >> 1990 "" "S Smith" >> 1990 UCLA "P Williams" >> 1990 Yale " K John" >> 1991 "" "K Evert" >> 1991 Oxford "K Evert" >> 1991 "" "K Evert" >> end >> >> replace Uni=trim(Uni) >> replace Prof=trim(Prof) >> compress >> >> gen byte nonmiss=!mi(Uni) >> >> //replace with last obs >> bys year Prof (nonmiss): /* >> */ replace Uni=Uni[_N] /* >> */ if nonmiss==0 >> >> l, noo sepby(year Prof) >> ************* >> >> joe j >> >> Thanks. (Your suggestion helped me create a variable that takes a >> numeric value, instead of the university name; this is definitely an >> improvement.) >> >> This is how the data looks like: >> >> Year University Professor >> >> 1990 Harvard S Smith >> 1990 --------- S Smith >> 1990 UCLA P Williams >> 1990 Yale K John >> >> 1991 --------- K Evert >> 1991 Oxford K Evert >> >> What I want is to replace the missing names above, in 1990 with >> Harvard and in 1991 with Oxford. >> >> On Thu, Oct 8, 2009 at 11:59 AM, Martin Weiss <martin.weiss1@gmx.de> >> >>> You should turn the string into a numeric variable via -encode-. Then >> -egen- >>> can go to work. Also provide an excerpt of your data and show what you >> want >>> to happen to them... >> >> joe j >> >>> In my data I have a string variable "University", which lists >>> university names. In some years the names are missing. Two other >>> variables I've are "Professor" and "Year". The same "Professor" and >>> "University" can occur multiple times in a year. >>> >>> The problem I have is that there are quite a few University names that >>> are missing. What I want to do is to replace as many missing >>> University names as possible, by assuming that: when a professor is >>> linked to a university at least once in a year, she is linked to the >>> same university during that year - so the missing university name when >>> her name occurs again in the same year can be replaced (why there are >>> missing university names is a complicated story:)). >> >>> I tried the following in Stata (it's foolish, I know): >>> >>> bysort year professor: egen University_all=mean(University) >>> >>> But I get the warning "type mismatch". >> > > * > * 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/ > * * 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/

**References**:**st: egen(mean or suchlike) for a string variable***From:*joe j <joe.stata@gmail.com>

**Re: st: AW: egen(mean or suchlike) for a string variable***From:*joe j <joe.stata@gmail.com>

**RE: st: AW: egen(mean or suchlike) for a string variable***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: AW: egen(mean or suchlike) for a string variable***From:*joe j <joe.stata@gmail.com>

**RE: st: AW: egen(mean or suchlike) for a string variable***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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