(* PS6.9 using DATA4-4 for estimating demand elasticities -- Section 6.11 *)
logs BUSTRAVL FARE GASPRICE INCOME POP DENSITY LANDAREA  
ols l_BUSTRA const l_FARE l_GASPRI l_INCOME l_POP l_DENSIT l_LANDAR  
omit l_DENSIT  
omit l_GASPRI  
omit l_FARE  
