get xi interval
get_xi_interval(Y = 1, X, methods = "Schennach")A list containing the lower (xi_lb) and upper (xi_ub) bounds of the xi interval.
A numerical vector representing the sample data of variable Y.
A numerical vector representing the sample data of variable X.
A character string indicating the method to use for calculating the xi interval. Supported methods are "Schennach" and "Schennach_loose". Defaults to "Schennach".
The "Schennach" method computes the xi interval by performing a test based on the
Schennach's theorem, adjusting the upper bound xi_ub if the test condition is met.
The "Schennach_loose" method provides a looser calculation of the xi interval without
performing the Schennach's test.