logit_integrand: Default integrand for the group-level propensity score
In inferference: Methods for Causal Inference with Interference

Computes the following function:

prod(r * plogis(X * fixef + b)^A * (1 - r * plogis(X * fixef+ b))^(1 - A)) * dnorm(sd = sqrt(ranef))

where r is the randomization scheme. X is the covariate(s) vectors. fixef is the vector of fixed effects. b is the random (group-level) effect. ranef is the random effect variance.

1	logit_integrand(b, X, A, parameters, allocation = A, randomization = 1)

`b`	vector argument of values necessary for `integrate`.
`X`	n by length(fixed effects) matrix of covariates.
`A`	vector of binary treatments
`parameters`	vector of fixed effect (and random effect if applicable). Random effect should be last element in vector.
`allocation`	The allocation strategy. Defaults to A so that is essentially ignored if allocation is not set to a value within (0, 1).
`randomization`	Randomization probability. Defaults to 1.