b. Test for the significance of the correlation.
c. What argument can you make to support the conclusion that lower levels of education cause low income?
Use the following data set to answer the questions. Do this one manually. a. Compute the correlation between age in months and number of words known. b. Test for the significance of the correlation at the. 05 level of significance.
c. Recall what you learned in Ch. 5 of Salkind( 2011) about correlation coefficients and interpret this correlation.
Age in months Number of words known 12 6 15 8 9 4 7 5 18 14 24 18 15 7 16 6 21 12 15 17 How does linear regression differ from analysis of variance?
Betsy is interested in predicting how many 75-year-olds will develop Alzheimer s disease and is using level of education and general physical health graded on a scale from 1 to 10 as predictors. 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 Alzheimer s disease.
c. With the four predictor variables( level of education, general physical health, and the two new ones that you name), draw out what the model of the regression equation would look like.
Joe Coach was curious to know if the average number of games won in a year predicts 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. Refer to the following data set:
Team Average no. of wins over 10 years Bowl?( 1 = yes and 0 = no) Savannah Sharks 12 1 Pittsburgh Pelicans 11 0 Williamstown Warriors 15 0 Bennington 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 assess 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 a 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?