TDT
Power Calculator
Wei-Min Chen, updated on 2/7/2002
TDT Power Calculator (TDT-PC) is a computer program to compute the statistical power of the Transmission/Disequilibrium Test (TDT), which is a powerful test for linkage in the presence of association.
Although power calculation via Monte Carlo computer simulation is accurate and general, it is time-consuming, not convenient for investigation, and impossible to do sample size calculations. TDT-PC computes the power of the TDT analytically, based on the most accurate asymptotic algorithms up to date, and is applicable in very general situations, where different parental disease status, multiple children, mixed family type and recombination events are considered. Routine algorithms for Monte Carlo simulations with significant improvements are also implemented in this program, to confirm and examine the analytical power calculation.
As a calculator to calculate the power of the TDT, TDT-PC has a user-friendly interface for every single power calculation. Using files as input, extensive and multiple investigations can be performed, which may serve as a very powerful tool for investigators. For further questions and comments, you are welcome to contact Wei-Min Chen at wechen@jhsph.edu.
Note: Power here refers to the statistical power or the required number of families based on samples drawn randomly from a population, under the alternative hypothesis of linkage and association. The only requirement for samples is that there must be at least an affected child for each nuclear family.
TDT Power
Calculator version 1.1.1 (2000)
Download PC1.1.1 for Windows & DOS Download PC1.1.1 for Solaris
PC1.1.1 is a sophisticated version having been under many
tests.
Download PC1.2.1 for Windows & DOS Download PC1.2.1 for Solaris
In version 1.2.1, algorithms underlying Monte Carlo
simulations are optimized. Computer simulations are very fast. This version also
has made several other minor corrections such as the format of numbers.
TDT Power Calculator version 1.3 (2002)
Multi-locus TDTs and multi-allelic TDT are implemented in TDT-PC 1.3.
TDT-EMM: multi-locus TDT using EM algorithm to estimate the frequency of
haplotypes, allowing missing data. 
(Fallin et al 2002)
TDT-B: multi-locus TDT using Bonferroni correction.
TDT-MA: multi-allelic TDT. (Spielman et al 1996)
Once our paper is published, this new powerful version of program will be available.
Future versions of TDT Power Calculator
Many other powerful nuclear family-based tests will be
implemented.
Acknowledgements:
During the development of this computer program, I received many helps. Plenty of RA time and support from Dr. Hong-Wen Deng and Dr. Kung-Yee Liang makes it possible for me to start this project. Thank them for providing me the great opportunity to implement various ideas. Since I am always the first user of this program, I have to spend plenty of extra time and efforts to make this program fast, robust and user-friendly. Thank Dr. Daniel Fallin, Dr. Kung-Yee Liang, and Dr. Terry Beaty for initialing and developing the TDT-EMM together. Many thanks to Dr. Daniel Weeks and other people for bug reporting.
Chen WM, Deng HW (2001) A general and accurate approach for computing the statistical power of the transmission disequilibrium test for complex disease genes. Genetic Epidemiol 21:53-67 [Abstract in PubMed] [98kb, in PDF format]
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