Exam 6: Correlation and Regression

A student wanted to know if there was a relationship between a person's alphabetical position and his or her academic performance as measured by points in a General Psychology class. Below are some hypothetical data. Alphabetical Position Points 2 18 5 19 8 15 14 14 20 13 26 11 (Real data exist in professor's grade books and might be available to someone who wanted to determine the degree of this relationship.)For these data, a. draw a scatterplot. b. calculate r. c. draw the regression line on your scatterplot, clearly identifying with large X's the two points you used to construct the line. d. predict the number of points made by a person whose alphabetical position is 13. e. interpret the results of the correlation coefficient in a simple sentence.

According to your text, the correlation between per capita income and violent crime rate in the 50 American states is

The mathematical method that the regression equation uses to fit a straight line is called the method.

The techniques in Chapter 6 accurately describe the relationship between two variables when the relationship is that of

With a correlation coefficient alone you can

Look at the three sets of distributions below and without doing any calculations, label them as positive or negative correlations. - 21 61 18 47 17 32 14 21 13 10 13 2

Quantification is the idea that

For the data below: a. Draw a scatterplot. b. On the scatterplot draw a regression line predicting self-esteem from IQ using any two points on the curve. c. Compute r. d. Interpret the results of your correlation coefficient in a simple sentence. IQ Self-Esteem Score 100 3 90 5 120 4 130 6 110 7

Which of the situations below expresses a positive correlation?

Two exist for one set of bivariate data.

Data Set 6-3 X Y 2 3 3 6 5 7 2 4 -For Data Set 6-3, $\Sigma$ XY is

Your text cautioned you about the appearance of regression lines. The caution was the appearances depend on

An experimenter wanted to determine whether a paper-and pencil test of spatial-relations ability was valid. (A valid test is one that measures what it claims to measure.) He gave the test to a group of 32 children. He then took groups of seven children into a large two-story house and organized games of hide and seek. After an hour of play, he administered a test that determined whether the children had learned the spatial organization of the house. Perform appropriate operations on the data below. Paper-Pencil House Paper-Pencil House 1 41 85 2 23 64 3 36 70 4 28 60 5 39 90 6 48 95 7 42 92 8 35 70 9 33 72 10 21 52 11 33 65 12 16 40 13 21 53 14 20 56 15 35 67 16 45 90 17 35 80 18 29 75 19 19 60 20 33 68 21 43 91 22 40 87 23 27 50 24 25 63 25 36 83 26 49 94 27 36 85 28 15 60 29 39 79 30 29 64 31 36 80 32

The regression equation described in your textbook is based on the largest-squared method.

Which of the following could not be a correlation coefficient?

When two distributions can be aligned with paired sets of scores the result is a distribution.

The regression coefficient, a, is

An academic aptitude test (X) is used by Enormous University to predict grade-point averages $( \hat { Y } )$ for prospective students. For these two variables r=.50 =4.62 =28 Sy=1.16 =2.13

Your text cautioned you about the appearance of regression lines. A graph of a correctly-drawn regression line may

Look at the three sets of distributions below and without doing any calculations, label them as positive or negative correlations. - 6 12 5 11 5 10 3 10 2 4 1 2 -2 1