1. Betsy is interested in predicting how many 75 year olds will develop alzheimer's disease and is using as predictors level of education and general physical health graded on a scale from 1 to 10. But she is interested in using other predictor variables as well. Answer the following questions.
a. What criteria should she use in the selection of other predictors? Why?
b. Name two other predictors that you think might be related to the development of Alzheimers disease.
c. With the four predictor variables (level of education and general physical health, ant the two new ones that you name), draw out what the model of the regression equation would look like.
4. Go to the library and locate three different examples of where the linear regression was used in a research study in your area of interest (healthcare). It's ok if the study contains more than one predictor variable. Answer the following questions for each study.
a. What is one independent variable? What is the dependent variable?
b. If there is more than one independent variable, what argument does the researcher make that these variables are independent from one another?
c. Which of the three studies seems to present the last convincing evidence that the dependent variable is predicted by the independent variable, and why?
5. Here's where you can apply the information in one of this chapters tips and get a chance to predict a super bowl winner! Coach was curious to know if the average number of games won in a year predicts a super bowl performance (win or lose). The X variable was the average number of games won during the past 10 seasons. The Y variable was whether the team ever won the super bowl during the past 10 seasons. Here is the data:
|
Team
|
Average number of wins over 10 years
|
Bowl? (1=yes and 0=no)
|
|
Savannah Sharks
|
12
|
1
|
|
Pittsburgh Pelicans
|
11
|
0
|
|
Williamstown Warriors
|
15
|
0
|
|
Bennigton Bruisers
|
12
|
1
|
|
Atlanta Angels
|
13
|
1
|
|
Trenton Terrors
|
16
|
0
|
|
Virginia Vipers
|
15
|
1
|
|
Charleston Crooners
|
9
|
0
|
|
Harrisburg Heathens
|
8
|
0
|
|
Eaton Energizers
|
12
|
1
|
A. How would you asses the usefulness of the average number of wins as a predictor of whether a team ever won a super bowl?
B. What's the advantage of being able to use the categorical variable (such as 1 or 0) as a dependent variable?
C. What other variables might you use to predict the dependent variable, and why would you choose them?
1. When does the obtained chi-square value equal zero? Provide an example of when this might happen.
2. Using the following data, test the question that an equal number of Democrats, Republicans, and independents voted during the most recent election. Test the hypothesis at the .05 level of significance. Do this by hand.
Political Affiliation
|
Republican
|
Democrat
|
Independent
|
|
800
|
700
|
900
|
|
|
|
|