Analysis of twin data ascertained through probands: The double-entry approach
Article first published online: 7 OCT 2003
© 2003 Wiley-Liss, Inc.
Volume 25, Issue 3, pages 225–235, November 2003
How to Cite
Hindsberger, C. and Bryld, L. E. (2003), Analysis of twin data ascertained through probands: The double-entry approach. Genet. Epidemiol., 25: 225–235. doi: 10.1002/gepi.10253
- Issue published online: 7 OCT 2003
- Article first published online: 7 OCT 2003
- Manuscript Accepted: 13 FEB 2003
- Manuscript Received: 28 OCT 2002
- linear regression;
- logistic regression;
- twin data
Twin pairs are sometimes included in studies because at least one of them is a proband, and conventionally the analysis of the data is based on the conditional distribution of the cotwin given the proband. In the case of more than one proband in each pair, an often used “ad hoc” method of analysis is to allow each twin to act as proband as well as cotwin. An example of this is the probandwise concordance, which is used as an estimate of the casewise concordance under incomplete ascertainment. In this paper, we show that the method of double entry under a regularity condition provides consistent estimates of parameters, but that conventional standard errors as well as a correction suggested by Stevenson et al. ( J. Child Psychol. Psychiatry 34:1137–1152) will be wrong. Instead, we recommend the use of an easily calculated sandwich estimator. We illustrate the method with twin data from a study of the genetic component in hand eczema. Genet Epidemiol 25:225–235, 2003. © 2003 Wiley-Liss, Inc.