Exam 5: Correlation and Regression

In the following correlation matrix, skinfolds were taken at four sites in an attempt to estimate percent body fat (%fat). Which variables have the LEAST in common? \%fat Chest Abd Calf Back \%fat 1.00 Chest .48 1.00 Abd .50 .62 1.00 Calf .58 .26 .11 1.00 Back .62 .23 .34 .42 1.00

Which of the following correlation coefficients provides the most predictive power?

You want to predict success on your second examination using information from your first examination score. The prediction equation is = 5X + 5, the mean on the first examination is 70, and the standard deviation of the second exam is 20. Determine the standard error of estimate for the prediction line if the coefficient of determination between the tests is .64.

If two predictor variables to be used in developing a multiple regression equation both correlate with the criterion variable at .75, what correlation coefficient between the two predictor variables would lead to the most efficient regression equation?

What does a negative value of r mean?

Which of the following is the LEAST likely use of a correlation coefficient?

Which of the following probably represents the relationship between VO₂max and time to complete a 1.5-mile run?

If variable X correlates at .84 with a criterion variable, what percent of variable X's variance is in common with the criterion?

What is the MOST important distinction between simple correlation and multiple correlation?

In the following correlation matrix, which two exams correlate the highest, and which two correlate the lowest? Exam 1 Exam 2 Exam 3 Exam Exam 1 1.00 -.025 -.740 -.36 Exam 2 -.025 1.00 .425 .011 Exam 3 -.740 .425 1.00 .682 Exam 4 -.366 .011 .682 1.00

Assume the figure below represents the association between self-reported physical activity (Y) and some predictor (X). Which of the following variables illustrates the amount of variance accounted for in this figure? Use the coefficient of determination to find the answer.

In general, which type of relationship is best to obtain?

Height of a building and amount of sway from wind

Which statistical method is used to estimate percent body fat based on age, gender, and skinfold measurements?

Miles driven on a tire and a measure of tire tread

Using the following correlation matrix, assume that you want to use two of the tests to measure the criterion. Which two tests would you use? Test A Test B Test C Criterion TestA 1.00 .56 .25 .75 TestB 1.00 .25 .00 TestC 1.00 .50

Which of the following represents multiple regression and the largest SEE?

Of the following, which correlation coefficient best describes the relationship between height and weight in healthy adults?

If the correlation coefficient between X and Y is .60, what proportion of the variance in Y is NOT predictable from X?

Given that the regression equation is Ŷ = .5X + 25 and the standard error of estimate is 3, what is the range of scores that would capture a person's true Y score 68% of the time, if that person had an X score of 30?