Question 1

Under what circumstances would you use the phi coefficient?

Accepted Answer

X = nominal variable and Y = nominal variable

Question 2

A positive correlation between two variables would be represented in a scatterplot as ______.

Accepted Answer

A) a line sloping upward 
B) a line sloping downward 
C) a horizontal line 
D) a vertical line 
A) a line sloping upward 
B) a line sloping downward 
C) a horizontal line 
D) a vertical line A

Question 3

A mediating variable is often called ______.

Accepted Answer

A) an independent variable 
B) a dependent variable 
C) a confounding variable 
D) none of these 
A) an independent variable 
B) a dependent variable 
C) a confounding variable 
D) none of these C

Question 4

Correlation coefficients describe every individual person in your data set.

Accepted Answer

A) True 
 B)False

Question 5

A negative correlation between two variables would be represented in a scatterplot as ______.

Accepted Answer

A) a line sloping upward 
B) a line sloping downward 
C) a horizontal line 
D) a vertical line 
A) a line sloping upward 
B) a line sloping downward 
C) a horizontal line 
D) a vertical line

Question 6

If X increases in value as Y decreases in value, what type of correlation exists?

Accepted Answer

A) positive 
B) negative 
C) neutral 
D) none 
A) positive 
B) negative 
C) neutral 
D) none

Question 7

Why will you rarely find a perfect correlation between any two variables?

Accepted Answer

The coefficient of determination is the

Question 8

A correlation coefficient comparing study time to grades is +.80.Can one then conclude that greater study time causes good grades? Why, or why not?

Accepted Answer

No, one could not conclude that greater

Question 9

The coefficient of determination is more precise than using a correlation coefficient alone.

Accepted Answer

A) True 
 B)False

Question 10

What is the numerical index that describes the relationships between two variables?

Accepted Answer

A) regression coefficient 
B) chi index 
C) correlation coefficient 
D) psi index 
A) regression coefficient 
B) chi index 
C) correlation coefficient 
D) psi index

Question 11

If the range of one or both of the variables is restricted, the correlation will be _______.

Accepted Answer

A) strengthened 
B) reduced 
C) the same 
D) It cannot be determined. 
A) strengthened 
B) reduced 
C) the same 
D) It cannot be determined.

Question 12

When you have a direct correlation, both variables change in the same direction.

Accepted Answer

A) True 
 B)False

Question 13

If the correlation between variables is .80, what is the coefficient of determination?

Accepted Answer

A) .20 
B) .34 
C) .64 
D) .80 
A) .20 
B) .34 
C) .64 
D) .80

Question 14

What type of correlation exists if the more you exercise, the less you will weigh?

Accepted Answer

A) negative correlation 
B) positive correlation 
C) indirect correlation 
D) a & c 
A) negative correlation 
B) positive correlation 
C) indirect correlation 
D) a & c

Question 15

If you wanted to compute the correlation between two interval-level variables, which type of correlation should you use?

Accepted Answer

A) Point biserial 
B) Phi 
C) Spearman rank 
D) Pearson 
A) Point biserial 
B) Phi 
C) Spearman rank 
D) Pearson

Question 16

The correlation between variable X and variable Y is represented by which of the following?

Accepted Answer

A) R(xy)2 
B) rₓᵧ 
C) rx(y) 
D) Rx / y 
A) R(xy)2 
B) rₓᵧ 
C) rx(y) 
D) Rx / y

Question 17

If the correlation between variables is .70, what percentage of the variance is shared variance?

Accepted Answer

A) 70% 
B) 51% 
C) 49% 
D) 30% 
A) 70% 
B) 51% 
C) 49% 
D) 30%

Question 18

What type of correlation exists if the more time you spend studying, the higher your test score will be?

Accepted Answer

A) negative correlation 
B) positive correlation 
C) direct correlation 
D) b & c 
A) negative correlation 
B) positive correlation 
C) direct correlation 
D) b & c

Question 19

Which of the following correlations would be interpreted a strong relationship?

Accepted Answer

A) .39 
B) .59 
C) .79 
D) .89 
A) .39 
B) .59 
C) .79 
D) .89

Question 20

Which of the following illustrates the range of possible values of Pearson's product-moment correlation coefficient?

Accepted Answer

A) -.01 to .01 
B) -1.0 to 1.0 
C) -2.0 to 2.0 
D) -3.0 to 3.0 
A) -.01 to .01 
B) -1.0 to 1.0 
C) -2.0 to 2.0 
D) -3.0 to 3.0

Exam 5: Ice Cream and Crime: Computing Correlation Coefficients

Under what circumstances would you use the phi coefficient?

A positive correlation between two variables would be represented in a scatterplot as ______.

A mediating variable is often called ______.

Correlation coefficients describe every individual person in your data set.

A negative correlation between two variables would be represented in a scatterplot as ______.

If X increases in value as Y decreases in value, what type of correlation exists?

Why will you rarely find a perfect correlation between any two variables?

A correlation coefficient comparing study time to grades is +.80.Can one then conclude that greater study time causes good grades? Why, or why not?

The coefficient of determination is more precise than using a correlation coefficient alone.

What is the numerical index that describes the relationships between two variables?

If the range of one or both of the variables is restricted, the correlation will be _______.

When you have a direct correlation, both variables change in the same direction.

If the correlation between variables is .80, what is the coefficient of determination?

What type of correlation exists if the more you exercise, the less you will weigh?

If you wanted to compute the correlation between two interval-level variables, which type of correlation should you use?

The correlation between variable X and variable Y is represented by which of the following?

If the correlation between variables is .70, what percentage of the variance is shared variance?

What type of correlation exists if the more time you spend studying, the higher your test score will be?

Which of the following correlations would be interpreted a strong relationship?

Which of the following illustrates the range of possible values of Pearson's product-moment correlation coefficient?

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