Deck 15: Correlation

Question 1

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 -1.00

Answer 1

either positive or negative near 0

Question 2

A researcher records the odometer reading 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.

Answer 2

C

Question 3

What is indicated by a Pearson correlation of r = +1.00 between X and Y?

A)each time X increases, there is a perfectly predictable increase in Y
B)every change in X causes a change in Y
C)every increase in X causes an increase in Y
D)All of the other 3 choices occur with a correlation of +1.00.

Answer 3

A

Question 4

The numerical value for a correlation _____.

A)can never be greater than 1.00
B)can never be less than -1.00
C)can never be greater than 1.00 and can never be less than -1.00
D)can be greater than 1.00 and can be less than -1.00

Question 5

What is the value of SP for the following set of data?

Question 6

A researcher measures IQ and weight for a group of college students.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 7

A scatter plot shows 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)0.80
B)0.40
C)-0.40
D)-0.80

Question 8

The results from a research study indicate that adolescents who watch more violent content on television also tend to engage in more violent behavior than their peers.The correlation between amount of TV violent content and amount of violent behavior is an example of

A)a positive correlation.
B)a negative correlation.
C)a correlation near zero.
D)a correlation near one.

Question 9

A set of n = 10 pairs of scores has ΣX = 20, ΣY = 30, and ΣXY = 74.What is the value of SP for these data?

A)74
B)24
C)14
D)-14

Question 10

A researcher measures driving distance from college and weekly cost of gas for a group of commuting college students.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 11

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 zero.
D)a correlation near one.

Question 12

Which of the following Pearson correlations shows the greatest strength or consistency of relationship?

A)-0.90
B)+0.74
C)+0.85
D)-0.33

Question 13

A set of n = 15 pairs of scores (X and Y values) has SS_X = 4, SS_Y = 25, and SP = 6.The Pearson correlation for these data is

A)6/100
B)6/10
C)6/(100/15)
D)6/(10/√15)

Question 14

What would the scatterplot show for data that produce a Pearson correlation of r = +.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 15

A set of n = 5 pairs of X and Y values has SS_X = 16, SS_Y = 4 and SP = 2.For these data, the Pearson correlation is _____.

Question 16

A set of n = 5 pairs of X and Y scores has ΣX = 15, ΣY = 5, and ΣXY = 10.For these data, the value of SP is

A)-5
B)5
C)10
D)25

Question 17

What is the value of SP for the following set of data?

Question 18

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 19

For which of the following Pearson correlations would the data points be clustered most closely around a straight line?

A)r = -0.10
B)r = +0.40
C)r = -0.70
D)There is no relationship between the correlation and how close the points are to a straight line.

Question 20

Which of the following best describes the Pearson correlation for these data?

Question 21

The Pearson and the Spearman correlations are both computed for the same set of data.If the Spearman correlation is r_S = +1.00, then what can you conclude about the Pearson correlation?

A)It will be positive.
B)It will have a value of 1.00
C)It will be positive and have a value of 1.00
D)There is no predictable relationship between the Pearson and the Spearman correlations

Question 22

The effect size for the data from an independent-measures t test can be measured by r² which is the percentage of variance accounted for.Which of the following also produces the value for r²?

A)squaring the Spearman correlation for the same data
B)squaring the point-biserial correlation for the same data
C)squaring the Pearson correlation for the same data
D)None of the other options will produce r².

Question 23

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 24

If the following seven scores are ranked from smallest (#1) to largest, then 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 25

Under what circumstances is the point-biserial correlation used?

A)in the same circumstances when a repeated-measures t test would be used
B)in the same circumstances when an independent-measures t test would be used
C)when both X and Y are dichotomous variables
D)when both X and Y are measured on an ordinal scale (ranks)

Question 26

For a two-tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?

A)there is a non-zero correlation for the general population
B)the population correlation is zero
C)there is a non-zero correlation for the sample
D)the sample correlation is zero

Question 27

Which of the following sets of correlations is correctly ordered from the highest to the lowest degree of relationship?

A)-0.91, +0.83, +0.10, -0.03
B)-0.91, +0.83,-0.03, -0.10
C)+0.83, +0.10, -0.91, -0.03
D)+0.83, +0.10, -0.03, -0.91

Question 28

A researcher obtains a Pearson correlation of r = 0.43 for a sample of n = 20 participants.For a two-tailed test, which of the following accurately describes the significance of the correlation?

A)The correlation is significant with α = .05 but not with α = .01.
B)The correlation is significant with either α = .05 or α = .01.
C)The correlation is not significant with either α = .05 or α = .01.
D)There is not enough information to evaluate the significance of the correlation.

Question 29

If the Pearson correlation is calculated for a sample of n = 20 individuals, what value for df should be used to determine whether or not the correlation is significant?

A)18
B)19
C)20
D)21

Question 30

What correlation is obtained when the Pearson correlation is computed for data that have been converted to ranks?

A)the Spearman correlation.
B)the point-biserial correlation.
C)the phi coefficient.
D)It is still called a Pearson correlation.

Question 31

Suppose the correlation between height and weight for adults is +0.40.What proportion (or percent) of the variability in weight can be explained by the relationship with height?

A)40%
B)60%
C)16%
D)84%

Question 32

How large a sample is needed for a correlation of r = 0.550 to be significant using a two-tailed test with α = .05?

A)n = 14
B)n = 13
C)n = 12
D)n = 11

Question 33

As the sample size gets larger, what happens to the size of the correlation that is needed for significance?

A)It also gets larger.
B)It gets smaller.
C)It stays constant.
D)There is no consistent relationship between sample size and the critical value for a significant correlation.

Question 34

For a group of graduating college seniors, a researcher records each student's rank in his/her high school graduating class and the student's rank in the college graduating class.Which correlation should be used to measure the relationship between these two variables?

A)Pearson correlation
B)Spearman correlation
C)point-biserial correlation
D)phi-coefficient

Question 35

Under what circumstances is the phi-coefficient used?

A)When one variable consists of ranks and the other is regular, numerical scores.
B)When both variables consists of ranks.
C)When both X and Y are dichotomous variables
D)When one variable is dichotomous and the other is regular, numerical scores.

Question 36

A set of n = 15 pairs of scores (X and Y values) produces a correlation of r = 0.40.If each of the X values is multiplied by 2 and the correlation is computed for the new scores, what value will be obtained for the new correlation?

A)r = 0.20
B)r = 0.40
C)r = 0.80
D)cannot be determined without knowing all the X and Y scores

Question 37

A Pearson correlation is computed for a sample of n = 18 pairs of X and Y values.What correlations are statistically significant with α = .05, two tails.

A)correlations between 0.468 and -0.468
B)correlations greater than or equal to 0.468 and correlation less than or equal to -0.468
C)correlations between 0.456 and -0.456
D)correlations greater than or equal to 0.456 and correlation less than or equal to -0.456

Question 38

The Pearson and the Spearman correlations are both computed for the same set of data.If the Pearson correlation is r = +1.00, then what can you conclude about the Spearman correlation?

A)It will be positive.
B)It will have a value of 1.00
C)It will be positive and have a value of 1.00
D)There is no predictable relationship between the Pearson and the Spearman correlations.

Question 39

For a sample of n = 16 individuals, how large a Pearson correlation is necessary to be statistically significant for a two-tailed test with ?

A)0.497
B)0.482
C)0.468
D)0.456

Question 40

If the following seven scores are ranked from smallest (#1) to largest, then what rank should be assigned to a score of X = 1? Scores: 1, 1, 1, 1, 3, 6, 6, 6, 9

A)1
B)2
C)2.5
D)4

Question 41

Assuming that other factors are constant, a correlation of r = -0.95 will result in more accurate predictions than a correlation of r = +0.70.

Question 42

The value for a correlation can never be greater than +1.00.

Question 43

For a positive correlation, decreases in X tend to be accompanied by decreases in Y.

Question 44

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.

Question 45

In a test for significance of a Pearson correlation for a sample of n = 30 individuals, you determine the critical value by using df = 29.

Question 46

The value for the sum of products (SP) is always greater than or equal to zero.

Question 47

A negative correlation means that decreases in the X variable tend to be accompanied by decreases in the Y variable.

Question 48

If you measured hearing acuity and age for a group of people who are 50 to 90 years old, you should obtain a negative correlation between the two variables.

Question 49

A correlation of r = -0.95 means that there is essentially no consistent relationship between X and Y.

Question 50

Using a two-tailed test with α = .05, a sample correlation of r = 0.355 for a sample of n = 30 individuals is large enough to conclude that there is a real correlation in the general population.

Question 51

If the data points in a scatter plot show a nearly circular pattern, then the correlation is near zero.

Question 52

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.

Question 53

A Spearman correlation of r_S = 0.45 is computed for a sample of n = 22 people.This is sufficient to conclude that there is a real (non-zero) correlation in the population.

Question 54

The value obtained for the sum of products, SP, determines the sign (+/-) for the correlation.

Question 55

A Pearson correlation of r = -0.90 indicates that the data points are clustered close to a line that slopes down to the right.

Question 56

For a two-tailed hypothesis test evaluating the significance of a correlation, the null hypothesis states that the sample correlation is zero.

Question 57

Suppose that there is a correlation of r = 0.41 between the amount of time that each student reports studying for an exam and the student's grade on the exam.This correlation would mean that there is a tendency for people who study more to get better grades.

Question 58

For a set of n = 10 pairs of scores with $\Sigma$ X = 10, $\Sigma$ Y = 40, and $\Sigma$ XY = 50, the sum of products of deviation is SP = 10.

Question 59

A researcher obtains a correlation of r = 0.390 for a sample of n = 25 individuals.This correlation is significant using a two-tailed test with $\alpha$ = .05.

Question 60

Suppose that there is a correlation of r = -0.41 between the amount of time that each student reports studying for an exam and the student's grade on the exam.This correlation would mean that there is a tendency for people who study more to get better grades.

Question 61

The Spearman correlation can be +1.00 or -1.00 even when there is no linear relationship between the two variables.

Question 62

The Spearman correlation is used to measure the relationship when both variables have been measured on an ordinal scale (both are ranks).

Question 63

The phi-coefficient is the correct correlation to use when both X and Y are dichotomous variables.

Question 64

The phi-coefficient is used to measure relationships for data that would also be appropriate for an independent-measures t test.

Question 65

If people are classified by age (over 30/under 30) and by political affiliation (Democrat/Republican), then the point-biserial correlation would be the proper technique to measure the relationship between the two variables.

Question 66

The sign of the correlation (+/-) is generally meaningless for the point-biserial correlation and the phi-coefficient.

Question 67

A researcher classifies people by gender and by whether or not they routinely watch the evening news on television.For the resulting data, the correct method for measuring the relationship between the two variables would be the phi-coefficient.

Question 68

For a two-tailed hypothesis test evaluating the significance of a Pearson correlation, the null hypothesis states that the correlation for the population is zero.

Question 69

If the Pearson correlation for a set of scores is equal to +1.00, then the Spearman correlation for the same scores would also be equal to +1.00.

Question 70

If the Spearman correlation for a set of scores is equal to +1.00, then the Pearson correlation for the same scores would also be equal to +1.00.
definitely