This function calculates the likelihood contributions of interval data
contributions4intervals(lower_bounds, upper_bounds, mymean, mysd)
a vector with the lower bounds of an interval covariate.
a vector with the upper bounds of an interval covariate.
a numeric for the expected value of the normal distribution (which is one of the parameters trying to be optimized so that the likelihood becomes maximized)
a numeric for the standard deviation of the normal distribution (which is one of the parameters trying to be optimized so that the likelihood becomes maximized)
a vector giving the likelihood contributions of the interval data.