Homework 11. Part 1. Name: Score: / null

Transcription

1 Name: Score: / Homework 11 Part 1 null 1 For which of the following correlations would the data points be clustered most closely around a straight line? A. r = 0.50 B. r = C. r = 0.10 D. There is no relationship between the correlation and how close the data points are to the line

2 2 Accepted characters: numbers, decimal point markers (period or comma), sign indicators (- For the following set of scores, Pearson's r is. (Round your final answer to two decimal places.) Answer Key: Accepted characters: numbers, decimal point markers (period or comma), sign indicators (- For the following set of scores, Pearson's r is. (Round your final answer to two decimal places.) Answer Key: 0.82

3 4 A Pearson correlation of r = between and indicates A. Each time increases, there is a perfectly predictable increase in B. Every change in causes a change in C. Every increase in causes an increase in D. All of the other 3 choices occur with a correlation of Answer Key: A 5 A set of n = 15 pairs of scores ( and values) has SS = 4, SS = 25, and SS = 6. The Pearson correlation for these data is A. 6 B C D Answer Key: D

4 6 Accepted characters: numbers, decimal point markers (period or comma), sign indicators (- For the following set of scores, Pearson's r is. (Round your final answer to two decimal places.) Answer Key: Accepted characters: numbers, decimal point markers (period or comma), sign indicators (- A set of n = 4 pairs of scores ( and values) has SS = 5, SS = 625, and SS = 50. The coefficient of determination (R 2 ) for these data is. (Round your answer to two decimal places.) Answer Key: A college professor reports that students who finish exams early tend to get better grades than students who hold on to exams until the last possible moment. The correlation between exam score and amount of time spent on the exam is an example of A. a positive correlation B. a negative correlation C. a correlation near one D. a correlation near zero

5 9 Identify the strength and direction of the relationship among the two variables shown in the graph. corr2.pdf A. strong, positive B. weak, positive C. weak, negative D. strong, negative 10 Sketch a scatterplot of the following data. Is the relationship between the variables positive or negative? A. positive B. negative

6 11 Identify the strength and direction of the relationship among the two variables shown in the graph. corr6.pdf A. weak, negative B. weak, positive C. strong, positive D. strong, negative Answer Key: D 12 In the following data, there are three scores (,, and Z) for each of the n = 5 individuals. Sketch a scatterplot for each of the relationships. The correlation between and is, between and Z is, and between and Z is. Z A. negative, positive, negative B. positive, positive, negative C. negative, negative, positive D. positive, negative, positive Answer Key: D

7 13 A scatter plot shows a set of data points that are widely scattered around a line that slopes down to the right. Which of the following values would be closest to the correlation for these data? A. r = B. r = C. r = 0.40 D. r = 0.80 Answer Key: A 14 The following graph displays a linear relationship between liking and self-disclosure. corr3.pdf True False Answer Key: False 15 Accepted characters: numbers, decimal point markers (period or comma), sign indicators (- - M - M ( - M ) ( - M ) = = -1 (1) * (-1) = Complete the above table and compute the covariance. The covariance (SS ) for these data is. Answer Key: 3

8 16 Identify the strength and direction of the relationship among the two variables shown in the graph. corr11.pdf A. weak, negative B. strong, negative C. strong, positive D. weak, positive Answer Key: A 17 Identify the strength and direction of the relationship among the two variables shown in the graph. corr14.pdf A. weak, positive B. weak, negative C. strong, positive D. strong, negative Answer Key: C

9 18 In a test for linear correlations, the assumption of normality means that A. the population of scores is normally distributed B. the population of scores is normally distributed C. for each score, the distribution of scores is normally distributed D. For each score, the distribution of scores is normally distributed E. All of the above Answer Key: E 19 Violation of the assumption of homoscedasticity means that A. the variances of and are negative B. the variance in is different from the variance in C. there is a negative correlation between and D. the variance in is the same as the variance in 20 Correlation values can range from -1.0 to True False Answer Key: True