Calculating statndard error of model parameters and gamma(no-purchase utility). Internal function that users should not call directly.
Sandwich(
eta_wo_k,
gamma,
Attr,
Choice_Set_List,
Alts_Same_Choice_Set,
Is_Purchase,
Base_Prod,
Num_Prod,
Num_Attr,
H,
cond
)numeric, estimated model parameters normalized for baseline product.
numeric, estimated gamma(no-purchase utility).
list, a set of data frame in which alternative specific variables.
list, product code included for each choice set.
list, for internal calculation, a list of data exposed to the same choice set.
list, for internal calculation, list of customers who are exposed to the same choice set who purchased the product. If purchased 1, otherwise 0.
numeric, the baseline product number
numeric, the number of all products in observed data.
numeric, the number of attributes in observed data.
matrix, a hessian matrix of the log-likelihood function.
numeric, the value associated with prop, which is the argument of the rmm function. (1-prop)/prop.
a value of standard error of estimate.