Joint density of birth weight and occurrence of death for the 2subpopulation case
Birthweight density:
is the mixing proportion
is the Gaussian density with mean and variance truncated at 0.
Probability of death conditioned on birth:
An infant of birth weight x in the ith subpopulation has probability of dying given in quadratic logistic form:
is the probability that this child is from subpopulation 1 given it has birth weight x.
