Exit ticket · Learning to Test Ideas: Controlled Experiments

Exit Ticket

1. What is the difference between an experiment and an observation?

1. Why is a control group essential?

1. A sports drink company surveyed 50 athletes who drink its product and 80% said they felt stronger. Identify two problems with this study and describe a better design.

Answer Key / Look-Fors: (1) An experiment deliberately changes a variable; an observation records what happens without manipulation. (2) It provides a baseline that shows what would happen without the treatment, so a difference can be attributed to the treatment. (3) Problems: no control group, self-report bias, no random assignment, athletes already chose the drink. Better: randomly assign athletes to the drink or a look-alike placebo, measure a performance variable (sprint time), keep training constant, and use a large sample.