Classify the following scenario as one-sided or two-sided test:

1. Test whether incoming students at a business school receive better grades in their classes if they have taken an online program covering basic material.
2. Test whether there is a difference between men's and women's usage of a mobile fitness app
3. Test whether the number of listeners of a music service has changed after they changed the user interface
4. Test whether users of a commercial website are less likely to make a purchase if they are required to set up a user account on the site

Thank you.