TV advertising in $ thousands
Radio advertising in $ thousands
Newspaper advertising in $ thousands
Number of units sold
Natural logarithm of sales
Natural logarithm of tv
Natural logarithm of radio
Natural logarithm of newspaper
= 1 if region 1 and = 0 otherwise
= 3 if region 3 and = 0 otherwise
= 2 if region 2 and = 0 otherwise