A mall food court manager wants to find out if hot drinks in…

A mall food court manager wants to find out if hot drinks in the winter increases time spent in the mall. To that end, she measures how long the average shopper stays in the mall on a particular day. The next day, she and her team hand out hot drinks at all of the mall entrances and then measures how long the average shopper stays in the mall that day. In this study, what is time spent in the mall considered?