Read chapter 1 in the text. Also review the material covered in lecture.
Reminder: This assignment will not be collected. Its purpose is to help you review the material we have covered in class and the text, but it is not to be viewed as an exhaustive list of topics/skills that you need to know.
Chp. 1
1.14, 1.16 (pp. 14-15)
Extra problems:
1. A researcher randomly selected 18 households, each of which had at least one child and one parent living in the home. He was interested in determining whether the number of hours of TV a child watches affects his/her grade point average (GPA) in school. In each of the households he administered a questionnaire to the parent(s) and asked whether or not the child watched more than 20 hours of TV per week. (Assume the parent gave an accurate report. Also, if there was more than one child, he used a random process to pick one of the children to ask questions about.) The researcher also got permission to get the child's GPA from school. The two datasets that he obtained are:
GPAs for kids who watched more than 20 hours of TV: 1.9, 2.0,
2.0, 2.1, 2.2, 2.3, 3.5, 3.5, 3.9
GPAs for the kids who watched less TV: 1.2, 3.3, 3.3, 3.5, 3.6, 3.8,
3.8, 3.9, 4.0
a. Was this an observational study or an experimental one?
b. Find the interquartile range of the GPAs for students who watched more than 20 hours of TV per week.
c. Find the median GPA for students who watched less than 20 hours of TV per week. d. Find the mean GPA for students who watched less than 20 hours of TV per week.
e. Describe the skew, if any, for the distribution of the GPAs of the kids who watched less than 20 hours of TV a week.
f. The researcher concluded that watching a lot of TV causes a child to perform poorly in school. Do you agree? Explain your answer briefly.
2. California is evaluating a new program to rehabilitate prisoners before their release; the object is to reduce the recidivism rate - the percentage who will be back in prison within two years of release. The program involves several months of ``boot camp'' - military-style basic training with very strict discipline. Admission to the program is voluntary. According to a prison spokesman, ``Those who complete boot camp are less likely to return to prison than other inmates.''
a. What is the treatment group in the prison spokesman's comparison? What is the control group?
b. Is the prison spokesman's comparison based on an observational study or a randomized controlled experiment?
c. True or false (and explain briefly): the data show that boot camp worked.