I have a dataset that I do not know how to calculate pairwise distances.
In sibpair linkage analysis a unit of analysis is the sibpair (2 brothers,
2 sisters, or a brother and sister). The covariate vector contains
information on each of the pair (e.g., two ages, two heights, two
weights). There is no way to order these covariates.
Consider the two ages on two sibpairs. Let age_ij be the age for the i^th
sibling in the j^th sibpair. The data matrix could be in any of the
following orders:
Sibpair Age1 Age2
1 age_11 age_21
2 age_12 age_22
or 1 age_21 age_11
2 age_12 age_22
or 1 age_11 age_21
2 age_22 age_12
or 1 age_21 age_11
2 age_22 age_21
We want to calculate the distance between the sibpairs since these are the
units of analysis.
We can arbitrarily invoke a rule (e.g., youngest is always the first age)
and use standard distance measures  but these are ad hoc and the genetic
linkage people are unsatisfied with this (though it is done routinely).
This is analogous to the difference between correlation and intraclass
correlation.
Any suggustions?
Bill

William D. Shannon, Ph.D.
Assistant Professor of Biostatistics in Medicine
Division of General Medical Sciences and Biostatistics
Washington University School of Medicine
Campus Box 8005, 660 S. Euclid
St. Louis, MO 63110
Phone: 3144548356
Fax: 3144545113
email: [log in to unmask]
web page: http://ilya.wustl.edu/~shannon
