Correlation

Question 1

What is bivariate distribution?

Answer 1

Pairs of observations on two variables.

Question 2

What technique is used to measure the degree of linear association?

Answer 2

Linear Correlation

Question 3

How do we typically plot bivariate data?

Answer 3

On a scatter diagram

Question 4

What is the key step for gaining marks when describing correlation?

Answer 4

Points have to be in context with the question.

Question 5

What is an explanatory variable?

Answer 5

The variable you control/independent variable

Question 6

What is a response variable?

Answer 6

The variable you measure/dependent variable

Question 7

What is the acronym for remembering explanatory and response variables?

Answer 7

DRIE

Dependent = Response

Independent = Explanatory

Question 8

What measure of correlation do we use?

Answer 8

Product moment correlation coefficient (r)

Question 9

What values can r take for correlation?

Answer 9

Anywhere between -1 and +1,

-1 represents perfect negative correlation.
+1 represents perfect positive correlation.

Question 10

What is another name for a line of best fit?

Answer 10

A regression line

Question 11

What co-ordinates must a regression line pass through?

Answer 11

_ _
X Y

Mean of X and Mean of Y

Question 12

What layout of formula do we use for correlation?

Answer 12

y = a + bx

Question 13

What is problematic about estimating values outside of a range using r?

Answer 13

This involves extrapolation, and the relationship may not be the same outside the range.