Exam 6: Correlation and Regression

The scores below are performance scores for six subjects on Trial 1 and Trial 30 of a test of motor skills. Trial 1 Trial 30 3 21 6 25 2 20 6 33 5 23 8 34 a. Compute r. b. What value for Trial 30 would be predicted from a Trial 1 score of 7? c. Explain the meaning of this correlation in a sentence or two.

If you have a regression equation

Data Set 6-3 X Y 2 3 3 6 5 7 2 4 -The correlation coefficient for Data Set 6-3 is

Suppose a small group of expert physicists and mathematicians held a joint conference. You, being an opportunistic sort, talked them all into taking two personality tests. The first test measured the need for achievement (N-Ach) and the second measured the need for affiliation (N-Aff), which is a desire for association with other people. Below are the scores. What conclusions can you reach about the relationship between need for achievement and need for affiliation among these scientists? Person X N-Ach Y N-Aff 1 28 12 2 27 10 3 25 14 4 24 18 5 24 11 6 23 15 7 23 16 8 23 19 9 22 22 10 21 20 11 19 18 12 18 24 13 17 25 14 15 23 15 13 26

A point that is always on the regression line is the point represented by

Given the regression equation, $\hat { Y }$ = 5 + 0.5X, where X is a score on an attitude scale and Y is a job satisfaction score, what satisfaction score would be predicted for an attitude score of 20?

For a bivariate distribution of data, there is(are)_____________correlation coefficient(s) and ___________regression line(s).

Which of the following is not a regression coefficient?

Assume you conduct a study to evaluate the relationship between the amount of time a child is read to and reading ability at age 15. You find a correlation coefficient of .04. This correlation suggests

Suppose you had a correlation coefficient on data from variables that had been truncated. In such a situation you might expect that the coefficient

"For the last ten years, I've used smaller and smaller amounts of pesticide, and each year I've had fewer bugs and larger yields."The correlation between amounts of pesticide and number of bugs is

Data Set 6-9 The correlation between high school GPA and college GPA is .50. Given the data that follow, your task is to predict college GPA. Mean 2.6 3.3 Standard Deviation 0.5 0.7 -In Data Set 6-9. For a person with a high school GPA of 4.0, the predicted college GPA is

The difference between correlation coefficients and a regression equation is that correlation coefficients

The regression coefficient, a, gives the slope of the regression line.

For a bivariate distribution with 10 pairs of scores, N = 10.

Which of the following statements describes a negative correlation?

In the regression equation $\hat { Y }$ = a + bX,

A Pearson correlation coefficient is appropriate to describe which of the situations below?

Data Set 6-6 X Y 1 4 2 3 3 2 -In Data Set 6-6, $\Sigma$ XYis

Alternative data set to go with scenario above. Weeks Items X Y 2 4 3 9 5 7 5 9 8 10 12 10 a. Compute r if appropriate;b. Computer the regression coefficients and give the regression equation;c. Predict the value of Y from an X value of 7.5;d. Interpret what you have found.