I have run a multinomial logistic model in SAS with 5 independant variables and I need to use the results from this model to make forecasts of use of care. I have used the predicted probabilities from the model and applied them to demographic forecasts per type of profile of client (age x gender) and now I need to use the exogenous variables (trend in disease, trend in unemployment, trend in handicap, etc) to forecast the use of care.
These exogenous variables are in my model also as independant variables and I have all coefficients and odds ratios for them. My question is how to apply the trend/forecast of these exogenous variables into my prediction?
How do I weight each of these exogenous variables in order to apply the growth of disease incidence, for example, into my forecast (demographic prediction)?
An example is how to apply disease incidence trend (ex. Alzheimer) into the forecast I have from the logistic regression? How do I calculate the weight of this variable?