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RE: st: RE: AW: RE: Evaluating a set of conditions
From
"Martin Weiss" <[email protected]>
To
<[email protected]>
Subject
RE: st: RE: AW: RE: Evaluating a set of conditions
Date
Wed, 23 Jun 2010 21:02:40 +0200
<>
Your own code returns "1" for id==11. Have you changed your mind?
***********
clear*
inp byte(id a b c d e)
1 0 0 1 0 0
2 1 0 1 1 0
3 . 1 1 1 1
4 0 1 1 0 1
5 1 0 0 0 0
6 1 . 1 1 0
7 0 0 0 0 0
8 1 . . . 1
9 1 0 0 0 0
10 1 . . 1 1
11 1 . 1 0 0
12 1 0 1 0 0
13 1 0 1 0 0
14 . 0 1 0 0
15 1 0 1 0 0
16 1 0 1 1 0
17 0 0 1 0 0
18 1 . . 0 .
end
egen anytwo = rowtotal(a b c d e), missing
egen missing = rowmiss(a b c d e)
replace anytwo = . if (anytwo==0 & missing>=2 & missing<.)
replace anytwo = . if (anytwo==1 & missing==1)
replace anytwo = . if (anytwo==1 & missing==3)
replace anytwo = . if (missing>=4)
gen disease = 1 if (a==1 & anytwo>=2 & anytwo<.)
replace disease = 0 if (a==1 & anytwo<2)
replace disease = 0 if a==0
replace disease =. if a==.
list in 11, noo
***********
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Thomas Speidel
Sent: Mittwoch, 23. Juni 2010 17:10
To: [email protected]
Subject: Re: st: RE: AW: RE: Evaluating a set of conditions
Thanks Martin and Nick. Here is an example where I have added more
missing and manually created "disease" to clarify how the missing
would impact the results:
id a b c d e disease
1 0 0 1 0 0 0
2 1 0 1 1 0 1
3 . 1 1 1 1 .
4 0 1 1 0 1 0
5 1 0 0 0 0 0
6 1 . 1 1 0 1
7 0 0 0 0 0 0
8 1 . . . 1 .
9 1 0 0 0 0 0
10 1 . . 1 1 1
11 1 . 1 0 0 .
12 1 0 1 0 0 0
13 1 0 1 0 0 0
14 . 0 1 0 0 .
15 1 0 1 0 0 0
16 1 0 1 1 0 1
17 0 0 1 0 0 0
18 1 . . 0 . .
Take a look at id==11 for example, where I don't have enough
information to determine disease presence.
Thomas Speidel
Quoting Nick Cox <[email protected]> Wed 23 Jun 06:59:44 2010:
> Yes, if there are missings it's more complicated than my initial answer
> could suggest.
>
> (a == 1) & (((b == 1) + (c ==1) + (d == 1) + (e == 1)) >= 2)
>
> would seem to match the possibilities better.
>
> Nick
> [email protected]
>
> Martin Weiss
>
> The result does seem to differ much, though, from the one Thomas
> evidently
> wants - as expressed by his example:
>
> *************
> clear*
> set obs 10000
> set seed 12345
>
> foreach var of newlist a b c d e{
> gen byte `var'=runiform()<.5
> replace `var'=. if runiform()<.15
> }
>
> //NJC
> gen disease_true = a & (b + c + d + e >= 2) /*
> */ if !missing(a, b, c, d, e)
>
> //Thomas
> egen anytwo = rowtotal(a b c d e), missing
> egen missing = rowmiss(a b c d e)
> replace anytwo = . if (anytwo==0 & missing>=2 & missing<.)
> replace anytwo = . if (anytwo==1 & missing==1)
> replace anytwo = . if (anytwo==1 & missing==3)
> replace anytwo = . if (missing>=4)
> gen disease = 1 if (a==1 & anytwo>=2 & anytwo<.)
> replace disease = 0 if (a==1 & anytwo<2)
> replace disease = 0 if a==0
> replace disease =. if a==.
>
> //Comparison
> compare disease_true disease
> as disease_true ==disease
> *************
>
> Nick Cox
>
> I think you need to be clear whether missing means true, false or
> indeterminate as far as this is concerned.
>
> Setting aside missings, as a, b, c, d, e are Booleans (1 = true, 0 =
> false) then
>
> gen disease_true = a & (b + c + d + e >= 2)
>
> is one way to do it. If missings make the problem indeterminate then
> tack on
>
> ... if !missing(a, b, c, d, e)
>
> Nick
> [email protected]
>
> Thomas Speidel
>
> Following up on my previous post:
> http://www.stata.com/statalist/archive/2010-06/msg00984.html
> here is an example for something I am trying to achieve in a
> nice/efficient/eleganty way.
>
> I have a number of dummies: a, b, c, d, e (missing values do exist)
> Disease=true if the following conditions are met:
>
> 1) a must be true AND
> 2) any two of b, c, d, e are true
>
> As I said missing values are crucial, especially when evaluating the
> second condition.
>
> My current program works, but I don't think it is efficient and it
> probably does things that are unnecessary:
>
> *******************************************
> egen anytwo = rowtotal(a b c d e), missing
> egen missing = rowmiss(a b c d e)
> replace anytwo = . if (anytwo==0 & missing>=2 & missing<.)
> replace anytwo = . if (anytwo==1 & missing==1)
> replace anytwo = . if (anytwo==1 & missing==3)
> replace anytwo = . if (missing>=4)
>
> gen disease = 1 if (a==1 & anytwo>=2 & anytwo<.)
> replace disease = 0 if (a==1 & anytwo<2)
> replace disease = 0 if a==0
> replace disease =. if a==.
> *******************************************
>
> I tried to play around with cond, but I found it was making this much
> more complicated then it is. I know I am complicating my life more
> than I need to which is why I am looking for alternative solutions.
>
> *
> * 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/
>
--
Thomas Speidel
*
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*
* For searches and help try:
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/