A company with a large sales force has implemented a pilot project to test new sales management software, hoping it will reduce the amount of time sales representatives spend on the computer. A random sample of sales reps is selected 30 of them with the old software and 35 with the new software. They are asked to keep track of the total amount of time they spend on the computer (in minutes) over a two-week period.
Is there evidence, at the 4% significance level, that the new software has reduced the amount of time sales reps spend on the computer? Are you sure that the new software is the cause of any difference you see?