Correlation and regression

Question 1

Define correlation

Answer 1

Correlation describes the strength and direction of the relationship between 2 continuous variables

Question 2

How is correlation described?

Answer 2

Correlation is described using scatterplots

Question 3

How is correlation measured?

Answer 3

measured by the correlation coefficient
r=1 (+ve relationship)
r= -1 (-ve relationship 
r=0.8 (strong)
r = 0.6 (moderate)
r = 0 (no relationship)

Question 4

If the p value is <0.05 than what is the relationship between the 2 variables?

Answer 4

linear relationship

Question 5

Correlation vs regression

Answer 5

Correlation
Summarises the strength and direction of the relationship between 2 variables (as a single value)

Regression
is a model
it uses one variable as the predictor (x) and the other as the response (y)
it finds an equation that best describes the relationship between the 2 variables

Question 6

What does the correlation coefficient squared indicate?

Answer 6

It gives the total proportion of variance in the response variable explained by the predictor variable

Question 7

The null hypothesis of correlation coefficient

Answer 7

There is no linear relationship between the 2 variables

Question 8

The null hypothesis of regression

Answer 8

The coefficient associated with each independent variable is equal to zero

Question 9

What is regression

Answer 9

Models the relationship between one or more predictor (independent) variables a a response (dependent) variable