Consider the following four studies:


I. A survey of newspaper editors examines their political views about foreign policy issues.
The analysis and conclusion involves a summary of the survey results.

II. Third graders are randomly sampled and assigned to an intensive language course. Their performance on a year-end language test is compared to students who did not take the course.

III. A study compares the change in home values between 1990-1999 in ten different neighborhoods in Seattle. The results show that there's a higher percentage change over time in less affluent neighborhoods.

IV. A study compares the durability of machine parts. The comparison looks at machines that were purchased with new metal alloy parts and at those purchased with old metal alloy parts.
The results show that durability increases with the use of the new alloy.

which examples are experiments?

a) III and IV only
b) I only
c) II only
d) I and II only
e) II and IV only