Directions:Read each question carefully and be sure to address the question posed. Use complete sentences when appropriate (i.e. Explain, Why or Why not?).Writing must be legible, otherwise, teacher has the right to not grade. PLACEin tray by due date.

1. In order to investigate a rumor that there is a greater than expected number of girls among the children of chemists, Science magazine conducted an informal survey of eight chemistry departments. A secretary in the chemistry department at Indiana University, Bloomington thought there might be something to this rumor and made sure that every one of the 34 faculty members in her department who have children responded to the Sciencesurvey. Altogether, these Indiana chemists have 53 (56%) girls and 41 (44%) boys.

1. Was this an observational study or an experiment? Justify your answer.

1. Does this study give convincing evidence that chemists produce more girl babies than boy babies? Why or why not?

1. What a headache!

Doctors identify "chronic tension-type headaches" as headaches that occur almost daily for at least six months. Can antidepressant medications or stress management training reduce the number and severity of these headaches? Are both together more effective than either alone?Investigators compared four different treatments: (1) antidepressant alone, (2) placebo alone, (3) antidepressant plus stress management, and (4) placebo plus stress management.

1. Outline the design of the experiment.

1. The headache sufferers named below have agreed to participate in the study. Use Table B at line 130 to randomly assign the subjects to treatments. (must show all work on this one).

Line 130 #s:

Acosta Duncan Han Liang Padilla Valasco

Asihiro Durr Howard Maldonado Plochman Vaughn

Bennett Edwards Hruska Marsden Rosen Wei

Bikalis Farouk Imrani Montoya Soloman Wilder

Chen Fleming James O'Brien Trujillo Willis

Clemente George Kaplan Ogle Tullock Zhang

So, finally: who is in what treatment?

1. Should I take the class?

A college allows students to choose either classroom or self-paced instruction in a basic economics course. The college wants to compare the effectiveness of self-paced and regular instruction. A professor proposes giving the same final exam to all students in both versions of the course and comparing the average score of those who took the self-paced option with the average score of students in the regular sections.

1. Who are the subjects of this study?

1. What is the explanatory variable?

1. What is the response variable?

1. What are some confounding variables that can make the results of this study worthless?

1. Surgery or not.

To compare surgical and nonsurgical treatments of intestinal cancer, researchers examined the records of a large number of patients. Patients who received surgery survived much longer (on the average) than patients who were treated without surgery. The study concludes that surgery is more effective than nonsurgical treatment.

1. Is this study an experiment? Why or why not?

1. What are the explanatory and response variables in this study?