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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

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

Subject |
st: RE: analyzing family data |

Date |
Mon, 21 Oct 2002 20:02:30 +0100 |

Devendra Amre MD., Ph.D. > I have the following 'family data' set that i wish to analyze. > > Subject family proband > diagnosis marker > 1 1 0 > 0 1 > 2 1 1 > 2 0 > 3 1 0 > 1 0 > 4 1 0 > 0 1 > and so forth for other families > > 1. I wish to estimate the frequency of families in which > the proband (i.e 1) has diagnosis 1 and is marker positive (i.e 1) There are FAQs which may be helpful here at How do I create variables summarizing for each individual properties of the other members of a group? http://www.stata.com/support/faqs/data/members.html This FAQ was substantially revised last month, after on-list and off-list interaction with Guillermo Cruces. How do I create a variable recording whether any members of a group (or all members of a group) possess some characteristic? http://www.stata.com/support/faqs/data/anyall.html For this problem, I would go bysort family : egen diagpos = sum((proband == 1) & (diagnosis == 1) & (marker == 1)) which counts how many observations in each family satisfy this triple criterion. Hence families with at least one such person will all be given positive values. If you want to count families not persons, follow with egen tag = tag(family) if diagpos count if tag ... if tag > 2. Further I wish to estimate the frequency of marker > positivity (being 1) among 'other family members' of > families where the proband==1 & diagnosis==1 and marker==1. We have tagged such families. First we get the family sum by family : egen npos = sum(marker == 1) if tag and then we subtract this person replace npos = npos - (marker == 1) to get the number of others in the family who are positive. Here, for example, marker == 1 evaluates to 1 if that condition is true. The treatment of true and false in Stata is surveyed in What is true and false in Stata? http://www.stata.com/support/faqs/data/trueorfalse.html Nick n.j.cox@durham.ac.uk * * 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/

**References**:**st: analyzing family data***From:*<devendra.amre@umontreal.ca>

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