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RE: st: RE: AW: RE: Evaluating a set of conditions
From
Thomas Speidel <[email protected]>
To
[email protected]
Subject
RE: st: RE: AW: RE: Evaluating a set of conditions
Date
Wed, 23 Jun 2010 13:13:54 -0600
While trying to simplify the problem for the list (my variables are
not actually called a, b, c, etc) I must have inadvertantly introduced
some problems. Sorry for the confusion.
Nonetheless, the variable called "disease" in the n=18 dataset is
indeed what I am trying to achieve.
Thomas
Quoting Martin Weiss <[email protected]> Wed 23 Jun 13:02:40 2010:
<>
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.
*
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--
Thomas Speidel
*
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* 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/
--
Thomas Speidel
*
* 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/