Returns the value of Owen's Q-function at given input arguments.
Details
Uses integrate() from package stats to perform the numerical evaluation of the
definite integral in Owen's Q.
See ../doc/BE_power_sample_size_excerpt.pdf in the package sub-directory /doc
for the definition of Owen's Q.
The arguments to the function must be scalars. No vectors allowed.
References
Owen, D. B. (1965)
"A Special Case of a Bivariate Non-central t-Distribution"
Biometrika, 52, 437-446.