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From |
Asadullah <gunnuox@yahoo.co.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Data managment- group characteristics |

Date |
Thu, 21 Aug 2003 07:00:51 -0700 (PDT) |

Hello, I am having trouble in figuring out how to create some peer variables for my data. I have a dataset of kids in households and i need to calculate variables that reflect the position of a kid (say, aged 6-17) among other kids (in same age group) in the residential neighbourhood. If i wanted to obtain simple peer variables, then the solution is to calculate the -peer variable- of interest for each kid (by excluding him/her from the calculation), following the rule explained in FAQ section on STATA webpage : http://stata.com/support/faqs/data/members.html With little modification of the rule, own siblings can also be net out from the above calculation of peer vars. Problem is in creating variables like, say “relative birth order” (RBO), for every kid in the sample using only data on -all other kids in the neighbourhood- where we need to: (a) exclude own siblings in calculation & (b) retain the individual kid (for whom the variable is being calculated) in calculation. For kids with no siblings, there is little problem. It is the presence of own siblings that i am finding difficult to deal with. IN contrast to common peer group variables that are constant for kids from same families, this (within neighbourhood) R/BO may be different for siblings of different age within a family. Some form of nested loop (may be as an extension of the cited FAQ) is necessary, but I haven’t been able to construct the general form of it. Once done, I can calculate lots of other variables (e.g. what % of kids in the peer group are older in age, of same age etc. etc.). Any help will be appreciated. I further elaborate my case below. Thanks. Asad. RBO (relative birth order) is calculated as: g RBO=(BO-1)/(Tot_KIDS-1) where, "BO" (absolute birth order) is: egen BO=rank(age*(include)),by(Nid) field But presence of own siblings mean that both BO and Tot_KIDS (total no. of other kids in neighborhood) are incorrect. For correct Tot_KIDS , we could follow the STATA FAQ (by Nick) ... g Tot_KIDS =. qui sum hid qui forvalues i = 1 / `r(max)' { g include=1 if hid!=`i' & age>=6 & age<18 egen Tot_KIDS_1=sum((age>=6 & age<18)*include),by(Nid) egen Tot_KIDS _2=sum((age>=6 & age<18)*include),by(family) replace Tot_KIDS = Tot_KIDS_1- Tot_KIDS_2 if hid==`i' drop include Tot_KIDS_* } For BO, however, i need a way to exclude own siblings while executing the following for each kid in the neighborhood: egen BO=rank(age),by(Nid) field Then, I guess, my problem is solved. Following is sample data where BO is the birth order (within neighborhood) variable to be calculated for each kid. “Nid” is neighborhood id, “family” is family id etc. Nid family person age BO 1 1 1 40 . 1 1 2 35 . 1 1 3 12 2 1 1 4 6 1 1 1 5 7 1 1 2 1 36 . 1 2 2 31 . 1 2 3 8 3 1 3 1 40 . 1 3 2 12 4 1 3 3 12 4 1 3 4 8 3 __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com * * 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: Data managment- group characteristics***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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