.  Smith thinks that drinking “Go” juice will increase the p…

.  Smith thinks that drinking “Go” juice will increase the productivity of his workers.  He puts his employees into two groups of 50 workers each and assigns each group the same task (stapling sets of papers).  Group A is given “Go” juice to drink while they work.  Group B is not given any juice.  After seven days, Smith counts how many stacks of papers each group has made.  Group A produces 2,000 more stacks per day than Group B.  What is the independent (experimental) variable in this experiment?