A physical therapist is interested in comparing four different physical therapy regimens for patients recovering from knee replacement surgery. The four treatment regimens to be studied are weight training, aquatic exercise, riding a bike, and walking.

Each treatment group will consist of 20 subjects who have recently had knee surgery. Each subject will be measured and given a condition score before starting their rehabilitation program and then measured again at the end of the program.

The change in an individual’s condition score will be analyzed.

(a) Is this study an experiment or an observational study? Why?

(b) What are the treatments in this study?

(c) What are the experimental units in this study?

(d) What is the response variable in this study?

(e) Is this a blinded experiment?