Ch4 - Correlation

Question 1

Bivariate Data

Answer 1

Data which has pairs of values for two variables

Question 2

Correlation

Answer 2

Describes nature of the linear relationship between two variables.

Question 3

When two variables are correlated:

Answer 3

• Consider the context of the question

- Use common sense to determine whether they have a casual relationship.

Question 4

Regression line of y on x

Answer 4

y = a + bx

Question 5

Coefficient b tells you the change in y for each unit change in x.

Answer 5

• Data positively correlated, b will be positive

- Data negatively correlated, b will be negative.

Question 6

When should you use the regression line?

Answer 6

To make predictions for values of the dependent variable that are within the range of the given data.

Question 7

What does X-axis show?

Answer 7

Explanatory variable

Question 8

What does Y-axis show?

Answer 8

Response variable

Question 9

When do two variables have a casual relationship?

Answer 9

If a change in one variable causes a change in the other. Just because two variables show correlation does not necessarily mean casual relationship.

Question 10

Least Squares Regression line

Answer 10

Straight line that minimises the sum of the squares of the distances of each point from the line

Question 11

Positive Correlation

Answer 11

One increases, other also increases.

Question 12

Negative Correlation

Answer 12

One increases, another decreases.