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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: using -cond- to create a indicator [was: Re: st: intcens: how to estimate mean and variance after intcens] |

Date |
Fri, 26 Oct 2012 08:59:22 +0100 |

Although I am fond of -cond()- I would usually write here generate wcgrp = wc>90&sex==1 | wc>80&sex==2 if wc < . Nick On Fri, Oct 26, 2012 at 8:37 AM, Maarten Buis <maartenlbuis@gmail.com> wrote: > On Fri, Oct 26, 2012 at 6:22 AM, PHAM Ngoc Minh wrote: >> I wish to create dummy variables containing missing (.), and thus used >> formula COND(IF, THEN, ELSE) but missing (.) no longer existed. An example >> as follows: >> >> I need to generate (wcgrp) from waist circumference (wc) as 1, 0 or missing >> (.), then typed: >> >> generate wcgrp = cond(wc>90&wc!=.&sex==1|wc>80&wc!=.&sex==2, 1, 0) >> >> but (wcgrp) had only 1 and 0, and missing was regarded as 0. > > What you want is a new variable that contains three possible values > (0, 1, .) but you give it values using a function that can only output > 2 values (one for when the expression is true and one for when the > expression is false), so that cannot work. Notice however that > -cond()- is working correctly in the sense that it did exactly what > you told it to do: it gives a 0 when the expression is false and the > expression is false when either the waist circumference is smaller > than some sex specific threshold or when wc is missing. > > Below are two possible solutions: > > generate wcgrp = cond(wc>90&sex==1|wc>80&sex==2, 1, 0) if !missing(wc) > > generate wcgrp = cond(wc>90&sex==1|wc>80&sex==2, cond(missing(wc), ., 1), 0) > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: using -cond- to create a indicator***From:*"PHAM Ngoc Minh" <pham@ri.ncgm.go.jp>

**References**:**using -cond- to create a indicator [was: Re: st: intcens: how to estimate mean and variance after intcens]***From:*Maarten Buis <maartenlbuis@gmail.com>

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