Click on the following links. Please note these will open in a new window.

1. Watch the following video about sampling: http://study.com/academy/lesson/probability-sampling-methods-definition-types.html
2. Watch the video about random sampling v. random assignment: https://youtu.be/D3Em-dka2Vc
3. Watch the video on probability: https://youtu.be/QpfMwA0z_1Y
4. Watch the video on calculating a Z score: https://youtu.be/1o-t_mVDDYQ