n_indep = identify_indep_vars (indep_vars, dep_var);
reader = casereader_clone (input);
reader = casereader_create_filter_missing (reader, indep_vars, n_indep,
n_indep = identify_indep_vars (indep_vars, dep_var);
reader = casereader_clone (input);
reader = casereader_create_filter_missing (reader, indep_vars, n_indep,