Determine if the study is experimental or observational
10. A health teacher wants to study the effects of regular swimming on a student’s ability to hold their breath. The teacher measures the length of time that a student can hold their breath. The teacher compares the times of those students who are on the swim team with those students who are not on the swim team.
11. Doctors want to study the effects on patients’ arthritis that occur when patients use a new arthritis ointment. The doctors give one group an ointment with no medicinal value and another group the new arthritis ointment.
10. This study is observational because the health teacher is merely comparing the times of students who are on the swim team with those who are not, without manipulating any variables.
11. This study is experimental because the doctors are assigning patients to different groups and manipulating the variable (the type of arthritis ointment) to study its effects on the patients' arthritis.