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# Re: st: how to create dummy for unique values across variables

 From Ana Gabriela Guerrero Serdan To statalist@hsphsun2.harvard.edu Subject Re: st: how to create dummy for unique values across variables Date Tue, 13 Nov 2007 10:04:36 -0800 (PST)

Thank you Maarten,

I finally managed to get it done.

regards,
Gaby

--- Maarten buis <maartenbuis@yahoo.co.uk> wrote:

> --- Ana Gabriela Guerrero Serdan
> <ag_guerreroserdan@yahoo.com> wrote:
> > I have data on victimes. The weapons used are
> > reported. Var cau*1 refers to the type of
> > aggression and cau1* to the weapon used. "-" means
> > no information.
> >
> > For some victimes there are two or more types of
> > aggression reported as well as type of weapon, up
> to
> > nine types. Im only including a few below.
> >
> >  Im trying to isolate cases in which only one
> weapon
> > is being used by creating a variable (dummy) that
> will
> > indicate that that victim was only agressed by
> only
> > that type of weapon.
>
> You can use logical operators here if you know that
> a
> true statement is given the value 1 and a false
> statement the value zero. So if you create a new
> variable using:
> gen weapon1 = cau12 != "-"
>
> and realize that cau12 != "-" is a logical statement
> saying: "cau12 is not equal to -", than you can see
> that the new variable weapon1 will contain a 1 if
> cau12 contains a weapon and a 0 if no information.
>
> This way you can make weapon2, weapon3, etc. The
> sum of weapon1 till weapon9 is the total number of
> weapons used. If this variable is called nweapons,
> you can make the dummy using:
> gen singleweapon = nweapons == 1
>
> see the example below:
>
> *----------------------- begin example
> -----------------
> drop _all
> input long victim   ///
>       str5 incident ///
>       str6 cau11    ///
>       str7 cau12    ///
>       str6 cau21    ///
>       str7 cau22    ///
>       str6 cau31    ///
>       str7 cau32
> 49711   d0096   Ground   Gunfire   Ground  Gunfire
> Ground  Knife
> 49713   d0097   Other       -      Other      -
> -        -
> 49712   d0097   -           -        -        -
> -        -
> 49714   d0097   Ground   Gunfire     -        -
> -        -
> 49595   d0098   Ground   Bombs       -        -
> -        -
> 49596   d0098   Ground   Bombs       -        -
> -        -
> 49599   d0099   Ground   Gunfire     -        -
> -        -
> 49598   d0099   Ground   Gunfire     -        -
> -        -
> 49597   d0099   Ground   Gunfire     -        -
> -        -
> 49602   d0100   Ground   Gunfire   Ground   Bombs
> -        -
> 49603   d0100   Ground   Gunfire   Ground   Bombs
> -        -
> 49601   d0100   Ground   Gunfire   Ground   Bombs
> Ground   Nuke
> end
>
> gen nweapons = 0
> forvalues i = 1/3 {
> 	gen weapon`i' = cau`i'2 != "-"
> 	replace nweapons = nweapons + weapon`i'
> }
> gen byte singleweapon = nweapons == 1
> tab singleweapon nweapons
> *------------------------ end example
> ---------------------------
> (For more on how to use examples I sent to the
> Statalist, see
> http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
>
> Hope this helps,
> Maarten
>
>
> -----------------------------------------
> Maarten L. Buis
> Department of Social Research Methodology
> Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
>
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
>
>
>
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Gaby Guerrero Serdan

Deparment of Economics
Royal Holloway, University of London
TW20 OEX
Egham, Surrey
England, UK
http://www.rhul.ac.uk/economics/About-Us/postgrads.html
http://www.flickr.com/photos/49939890@N00/

Tel: +44 7912657259

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