Assume you have daily retail sales data and hypothesize that sales are always higher on weekends than during the work week. You should include a dummy variable

Select one:

a.for "weekend" which equals one on Saturday and Sunday and zero otherwise.

b.for Saturday ( =1 on Saturday, =0 otherwise) and another dummy variable for Sunday ( =1 on Sunday, =0 otherwise).

c.for "weekend" ( =1 on Saturday and Sunday, =0 otherwise), and another dummy variable for "work week" (=1 for Monday-Friday, =0 otherwise).