The Variables

Eight total explanatory variables were used to test this study.

Day of the week

We wanted to find out how much each day of the week affected sales, so we used 5 dummy variables to represent Tuesday through Saturday, using Monday as the base.

In the SAS program we assigned the following variables:
d1 = Tuesday
d2 = Wednesday
d3 = Thursday
d4 = Friday
d5 = Saturday

Month

To see if the holidays were an important factor towards sales, M1 was assigned as a dummy variable for the month of December.  This covers the holiday season up to New Year's Eve.

Snowfall

To see if snowfall has any affect on daily sales, we assigned a dummy variable to represent whether or not snowfall was present that day.

Coupons

During the months of November and December, no coupons were used as a method of advertising.  However, in the month of January 2004 coupons were available.

Therefore, we assigned a dummy variable as to whether or not a coupons were available at the time of sale.