The article “Rocker Shoe Put to the Test: Can it Really Walk the Walk as a Way to Get in Shape?” (USA TODAY, October 12, 2009) describes claims made b

A shoe-manufacturing company claims that one of their shoe lines helps the wearer to “get into shape without going to the gym”.
In order to investigate the claim of the company, a study may be conducted with the help of volunteers, using the following steps:
- Form two groups, say, Group A and Group B.
- Consider 200 volunteers for the study. Measure the fitness level of each of the volunteers before beginning the study.
- Assign 100 volunteers randomly to Group A and the remaining 100 volunteers to Group B.
- Now, each of the 200 volunteers must perform some physical activities for a certain time period, say 2 months.
- The difference between Group A and Group B should be in their forms of physical activities and in the types of shoes they wear. The volunteers in Group A should perform some activities that are different from the kind of activities performed in a gym, while wearing the curved-sole sneakers. On the other hand, the volunteers in Group B should perform some physical activities that are comparable to the kind of activities performed at a gym, without wearing the curved-sole sneakers.
- After 2 months, measure the fitness level of each volunteer again, and compare the overall improvement in fitness levels of the volunteers in Group A with those in Group B.
Observational study:
An observational study is defined as a study, in which, the explanatory variables are not manipulated by the researcher, the researcher closely observes the characteristics of a population and then draws conclusions regarding that population or compares between two or more populations.
Experiment:
An experiment is defined as a study, in which, the explanatory variables are manipulated by the researcher to study their effects on the response variable, which is the variable of interest.
In the study designed above, the explanatory variables are the forms of physical activities and the types of shoes worn during such activities. The researcher manipulates these two explanatory variables and then observes the changes in the fitness levels after such manipulations.
Thus, the designed study is an experiment.