chapter 6

Question 1

The values of a correlation coefficient
range from:

Answer 1

• 1 to +1

Question 2

A correlation coefficient provides what
information about the relationship
between the two variables?

Answer 2

Strength (magnitude) and
direction

Question 3

A relationship between two variables best
described by a straight line is said to be:

Answer 3

Linear

Question 4

Which test?
Goal: Explore whether an association
exists
X: Ratio
Y: Ratio
Relationship: Linear

Answer 4

Pearson r (Pearson product-
moment correlation)

Question 5

r2, a measure of the strength of a
relationship, is know as:

Answer 5

The coefficient of
determination

Question 6

All of the points on the scatterplot fall on
the line. This relationship is said to be:
______________.

Answer 6

Perfect
(Partial credit for
“unlikely!”)

Question 7

Which test?
Goal: Explore whether an association
exists
X: Interval
Y: Ratio
Relationship: Monotonic

Answer 7

Spearman’s r (Spearman’s
rank-order correlation,
Spearman’s rho, rs)

Question 8

Restricting the range of a variable (X or Y)
will likely ___________ the correlation
coefficient.

Answer 8

Lower

Question 9

__________ scores can drastically alter the
magnitude of a correlation.

Answer 9

Extreme

Question 10

The four explanations of a correlation are:

Answer 10

1. Correlation between X and
   Y is spurious.
2. X is the cause of Y
3. Y is the cause of X
4. A 3rd variable is the cause
   of the correlation between
   X and Y

Question 11

Characteristics of relationships:
Direction

Answer 11

negative: x goes up, y goes down
positive: x goes up, y goes up

Question 12

Characteristics of relationships:
Form

Answer 12

linear is most common

Question 13

Characteristics of relationships:
Strength

Answer 13

degree of relationship

Question 14

the shape of a relationship can be determined by a _______

Answer 14

scatterplot

Question 15

More scatter in correlational data means

Answer 15

less significant the correlation is

Question 16

less scatter in correlational data means

Answer 16

the data is more linear, so there is more significant correlation

Question 17

what is the most common correlation coefficient

Answer 17

Pearson r

Question 18

pearson r can only be measured in what scales

Answer 18

interval or ratio data

Question 19

a specific measure of correlation is called ____

Answer 19

correlation coefficient

Question 20

pearson r is always between

Answer 20

-1 and 1

Question 21

the closer to -1 or 1, the ___ the relationship

Answer 21

stronger

Question 22

pearson r formula

Answer 22

degree to which X and Y vary together
_______________________________
degree to which X and Y vary separately

Question 23

Step 1 in solving for Pearson r

Answer 23

Compute SP
∑XY - (∑X)(∑Y)
_________
n

Question 24

Step 2 in solving for Pearson r

Answer 24

Compute SSₓ
∑X²- (∑X)²
_________
n

Question 25

Step 3 in solving for Pearson r

Answer 25

Compute SSᵧ
∑Y²- (∑Y)²
_________
n

Question 26

Step 4 in solving for Pearson r

Answer 26

Compute Pearson r
r = SP
___________
√ SSₓ SSᵧ

Question 27

What is the most common technique for measuring the strength of a correlation

Answer 27

Coefficient of Determination

Question 28

What is the equation for Coefficient of Determination)

Answer 28

r² = just square Pearson r

Question 29

if the correlation coefficient is
r = .10, whats the effect size?

Answer 29

small

Question 30

if the correlation coefficient is
r = .30, what’s the effect size?

Answer 30

medium

Question 31

if the correlation coefficient is
r = .50, what’s the effect size?

Answer 31

large

Question 32

When is Spearman’s Rank Order Correlation used?

Answer 32

When both variables are based on ordinal ranking

Question 33

What is the formula for Spearman’s Rank?

Answer 33

rₛ = 1 - 6 ∑ Dᵢ²
________
N³ - N