PSYC355 : Quiz #5- Correlation

PSYC355 / Quiz #5: Correlation Question 1 2.5 / 2.5 pts The numerical value for a correlation ranges between ________ and ________. a. 0; 1.00 b. –1.00; 1.00 c. negative infinity; positive infinity d. –1.00; 0 Question 2 2.5 / 2.5 pts What would the scatter plot show for data that produce a Pearson correlation of r = +0.88? a. Points clustered close to a line that slopes up to the right b. Points clustered close to a line that slopes down to the right c. Points widely scattered around a line that slopes up to the right d. Points widely scattered around a line that slopes down to the right Question 3 2.5 / 2.5 pts A set of n = 5 pairs of X and Y scores has Σ X = 15, Σ Y = 5, and Σ XY = 10. For these data, what is the value of SP ? a. -5 b. 5 c. 10 d. 25 Question 4 2.5 / 2.5 pts A set of n = 15 pairs of scores (X and Y values) has SS X = 4, SS Y = 25, and SP = 6. What is the Pearson correlation for these data? a. 6/100 b. 6/10 c. 6/(100/15) d. 6/(100–15)) Question 5 2.5 / 2.5 pts If the following seven scores are ranked from smallest (#1) to largest, what rank should be assigned to a score of X = 6? Scores: 1, 1, 3, 6, 6, 6, 9 a. 3 b. 4 c. 5 d. 6 Question 6 2.5 / 2.5 pts What is indicated by a positive value for a correlation? a. Increases in X tend to be accompanied by increases in Y b. Increases in X tend to be accompanied by decreases in Y c. A much stronger relationship than if the correlation were negative d. A much weaker relationship than if the correlation were negative

Question 7 2.5 / 2.5 pts Which correlation should be used to measure the relationship between gender and grade point average for a group of college students? a. Pearson correlation b. Spearman correlation c. Point-biserial correlation d. Phi-coefficient Question 8 2.5 / 2.5 pts A researcher records the age and price for a group of used Hondas. What kind of correlation is likely to be obtained for these two variables? a. A positive correlation b. A negative correlation c. A correlation near zero d. A correlation near one Question 9 2.5 / 2.5 pts The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation? a. A positive correlation near 0 b. A negative correlation near 0 c. Either positive or negative near 0 d. A value near +1.00 or –100 Question 10 2.5 / 2.5 pts A set of n = 10 pairs of scores has Σ X = 20, Σ Y = 30, and Σ XY = 74. What is the value of SP for these data? a. 74 b. 24 c. 14 d. -14 Question 11 2.5 / 2.5 pts A positive correlation between height and weight indicates that taller people tend to weigh less, on average, than shorter people. a. True b. False Question 12 2.5 / 2.5 pts If the value of the Pearson correlation is r = +1.00 or –1.00, then all data points in a scatter plot fit perfectly on a straight line. a. True b. False Question 13 2.5 / 2.5 pts A researcher obtains SS X = 20, SS Y = 5, and SP = 7 for a set of n = 25 pairs of scores. The Pearson correlation for these scores is r = 7/10 = 0.70.