Calculates the IPW for a single group. Used by wght_matrix to
create a matrix of weights for each group and allocation scheme.
wght_calc(parameters, integrand, allocation, integrate_allocation = TRUE, ...)vector of parameter values
function to pass to the argument 'f' of integrate.
the allocation ratio for which to compute the weight
Indicator of whether the integrand function uses the allocation parameter. Defaults to TRUE.
other arguments passed to integrand.
scalar result of the integral
If allocation is an argument in the integrand function and
integrate_allocation == TRUE, then the weight is calcuated as:
$$\frac{1}{Pr(A|X)}$$
Otherwise, the weight is computed by: $$\frac{\prod_{j=1}^n \alpha^A_j (1 - \alpha)^(1- A_j)}{Pr(A|X)}$$