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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Need clarification regarding egen total option |

Date |
Thu, 14 Feb 2013 01:08:25 +0000 |

The help for -egen- itself provides what you need. The function -total()- (itself not an option) is explained as total(exp) [, missing] creates a constant (within varlist) containing the sum of exp treating missing as 0. The expression exp is in turn age age >= 18 The second expression is true or false, and therefore evaluates as 1 if true and 0 if false. The effect, as you observe, is to count. For much more discussion, see http://www.stata.com/support/faqs/data-management/true-and-false/ Nick On Wed, Feb 13, 2013 at 9:49 PM, Michael Stewart <michaelstewartresearch@gmail.com> wrote: > I am trying to find the behaviour of the egen total function > > Let's see the following three commands > > .1) bysort fam:egen total1=total( age ) ==> this cmd sums > the age across observations per family > > 2). bysort fam:egen total2=total( age>=18 ) ==> this cmd COUNTS > the number of nonmissing values for age per family if > 18 > > 3). bysort fam:egen total3=total( age) if age >=18 ==> this cmd > again sums the age across observations per family if >18 > > why does the total option sums the ages when the option is total( age > ) where as gives the number of observations if total( age>=18 ) > option is present * * 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/

**References**:**st: Need clarification regarding egen total option***From:*Michael Stewart <michaelstewartresearch@gmail.com>

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