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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

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

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: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Thomas Speidel Sent: Mittwoch, 23. Juni 2010 17:10 To: statalist@hsphsun2.harvard.edu 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 <n.j.cox@durham.ac.uk> 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 > n.j.cox@durham.ac.uk > > 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 > n.j.cox@durham.ac.uk > > 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 * * 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/

**Follow-Ups**:**RE: st: RE: AW: RE: Evaluating a set of conditions***From:*Thomas Speidel <thomas@tmbx.com>

**References**:**st: Evaluating a set of conditions***From:*Thomas Speidel <thomas@tmbx.com>

**st: RE: Evaluating a set of conditions***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: AW: RE: Evaluating a set of conditions***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**st: RE: AW: RE: Evaluating a set of conditions***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: AW: RE: Evaluating a set of conditions***From:*Thomas Speidel <thomas@tmbx.com>

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