In this example, group by columns gender and marital_status result in 2x4=8 models being built.
call twm.td_analyze('linear','database=twm_source;tablename=twm_customer;columns=age,years_with_bank,nbr_children;dependent=income;outputdatabase=twm_results;outputtablename=twm_linear3;groupby=gender,marital_status');