Quan - Regression

Question 1

Regression =

Answer 1

use one variable to predict the other

• use to investigate casual relationship between 2 interval variables
• find the effect of the IV on a DV

Question 2

Regression analysis needs what variables?

Answer 2

2 interval level variables
normally distributed - histogram
share a linear relationship - scatterplot

Question 3

What visual aid is used in regression?

Answer 3

Scatterplot

Question 4

Why does regression use scatterplots?

Answer 4

Line of best fit
- calculated by measuring the distance between all the data
points and every possible line that can be drawn through them
- By choosing the line with the lowest total distance (i.e. the lowest error) we can use this for the purposes of prediction

Question 5

REGRESSION is the process of

Answer 5

The line of best fit is drawn through the data points and summarizes the relationship between two variables

Question 6

Line of best fit important becuase

Answer 6

line of best fit is used to understand how changes in the
independent variable causes changes in the dependent variable
can predict the values of the dependent variable from the values of the independent variable. This is known as regression analysis

Question 7

Regression is particularly sensitive to outliers

Answer 7

 They influence significantly the slope of the regression line
 We can easily visualise outliers with scatterplots
 Do not delete outliers without justifying theoretically the significance
of their presence

Question 8

R2

(coefficient of determination)

Answer 8

= measure of ‘model fit’
- Pearson’s correlation coefficient squared
- R2 tells us how much of the variance in the dependent
variable is explained by the independent variable