Sib-pair Command: tetrachoric

Class	Global Utility
Name	tetrachoric
Arguments	<prevalence> <recurrence risk ratio>

Calculate tetrachoric correlation equivalent to given recurrence risk ratio and trait prevalence. This is useful for estimating heritability under the multifactorial threshold model.

Example:

#
# For a trait with lifetime risk of 5%, a sibling recurrence risk ratio
# of 2 corresponds to a MFT heritability of 37%
#
>> tetrachoric 0.05 2
0.18537521215764666