chapter 14

Question 1

What are correlations? What will and won’t they tell us?

Answer 1

Correlations: the relationship between two variables
- will provide that a relationship exists & if it’s positive/negative
- will NOT provide if it is a cause and effect relationship

Question 2

positive correlation

Answer 2

two variables change in the same direction

Question 3

negative correlation

Answer 3

two variables change in opposite directions

Question 4

Range of Pearson’s R & meaning

Answer 4

range: -1 up to 1
-1: perfectly negative linear relationship
1: perfectly positive linear relationship

Question 5

Problems that can distort Pearson’s R

Answer 5

• restricted ranges
• outliers

Question 6

alternatives to pearson’s r

Answer 6

• spearman correlation
• point- based correlation
• phi-coefficient

Question 7

When to use Spearman correlation

Answer 7

1. when examining the relationship between ordinal variables (ranked, birth order)
2. when the form of the relationship between two variables are curved/exponential

Question 8

When to use the point-based correlation

Answer 8

when one variable is dichotomous (yes/no answer) and the other is on an interval/ratio scale
- CLOSELY RELATED TO THE INDEPENDENT MEASURES T-TEST

Question 9

When to use the Phi-Coefficient

Answer 9

when variables are BOTH dichotomous (yes/no)

Question 10

How do you calculate SP?

Answer 10

The sum total of (X-Mx)(Y-My)

Question 11

How do you calculate SS?

Answer 11

The sum total of (X-Mx)^2

• can be substituted for Y-My

MUST BE TO THE SECOND POWER!!!!