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From |
gcruces@worldbank.org |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Extensions to: Creating variables recording properties of the other membersof a group |

Date |
Wed, 28 Aug 2002 17:19:50 -0400 |

When working with twin household/individual datasets, this is one of the most useful FAQs: http://www.stata.com/support/faqs/data/members.html However, there are a few issues I couldn't solve with the information included there, or not efficiently at least. I would like to solve my problem and, if worthwhile, write an extension of the FAQ. The problem refers to the fact that sometimes you may need to record for one individual the properties not of the whole group, but of another member of the group in particular. In my example, I have a household survey where I don't have direct information about the number of kids of each individual, but I have something like this: hhid and member are just the household id and number of member. Variables fatherm and motherm tell you the number of the member of the father and the mother, if in the household: hhid member fatherm motherm 1 1 - - 1 2 - - 1 3 1 2 1 4 1 2 1 5 1 2 2 1 - - 2 2 - 1 2 3 - 2 ... Family one is a couple with three kids. Family two is a grandma, the daughter, and a grandchild. I want to create the variable ownkids that gives me the number of own kids living in the house: hhid member ownkids 1 1 3 1 2 3 1 3 0 1 4 0 1 5 0 2 1 1 2 2 1 2 3 0 My force brute solution, which makes a lot of unnecessary comparisons and takes very long (because I generate and drop many variables) is of the form: with maxmem being the number of members of each household (group i, max is the number of groups), forvalues i = 1/`max' { qui sum member if group==`i' local maxmem=r(max) forvalues j = 1/`maxmem' { di "-----------Household number `i', number of members: `maxmem'" forvalues k = 1/`maxmem' { di "Household `i', member `j', comparing with `k'" qui gen a=motherm==`j' if member==`k'&group==`i' qui egen b=max(a) qui replace mkids=mkids+b if member==`j'&group==`i' drop a b qui gen a=fatherm==`j' if member==`k'&group==`i' qui egen b=max(a) qui replace fkids=fkids+b if member==`j'&group==`i' drop a b } } } This creates two variables, mkids and fkids, which are the number of kids for mothers and fathers. For each member of the household, I compare if . The egen, replace, drop, takes very long, and even longer if the dataset in memory is large (I had to partition the dataset in 25 parts to make this run faster). The main problem (the main awkwardness in this program) is that I gen, egen, etc. because I could not just create a scalar that reflects the value of a variable for one precise observation, something of the form (which of course doesn't work): local a=mother==`j' if member==`k'&group==`i' (meaning: mother etc. should refer to the observation: member==`k'&group==`i') I coudn't use something like motherm[_...] becauseI was not using by: ... . What I would like to know if there are more efficient ways of doing this (I'm sure there are!). Thank you all *************************** Guillermo Cruces * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: Extensions to: Creating variables recording properties of the other members of a group***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: RE: Extensions to: Creating variables recording properties of the other members of a group***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: Re: Extensions to: Creating variables recording properties of the other members of a group***From:*"Marcela Perticara" <mperticara@uahurtado.cl>

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