SCATTERPLOT AND PERSON’S PRODUCT-MOMENT CORRELATION COEFFICIENT.

Exercise 2e AND 2F

A visual display of the relationship between two numerical variables.

SCATTERPLOTS

ANALYSINGSCATTERPLOTS

SCATTERPLOT GALLERY

POSITIVE RELETIONSHIP

NEGATIVE RELATIONSHIP

PERFECT LINEAR RELATIONSHIP

NO LINEAR RELATIONSHIP

DESCRIBE THIS CORRELATION

SCATTERPLOT

Decide whether or not a relationship exists between the variables and, if it does, comment on whether it is positive or negative; weak, moderate or strong: and whether or not it has a linear form

example

Data showing the average weekly number of hours studied by each student in year 12 at Strathmore Secondary College and the corresponding height of each student.

PEARSON’S PRODUCT-MOMENT CORRELATION COEFFICIENT

PEARSON’S PRODUCT-MOMENT CORRELATION COEFFICIENT

PLEASE ADD THIS TO YOUR NOTES!!!

THIS IS FOUND ON PG 87 OF YOUR TEXTBOOK.

EXAMPLE

There is a formula, but r is often done using CAS calculator. There are two limitations when using ‘r’:1. Since r measures the strength of a linear relationship, it

would be inappropriate to calculate r for data which are not linear.

2. Outliers can bias the value of r. Therefore, it will make it an unreliable measure of the strength of that linear relationship.

CALCULATING ‘R’ AND THE COEFFICIENT OF DETERMINATION

WE MUST DRAW A SCATTERPLOT FIRST IN ORDER TO CHECK FOR A LINEAR FORM BEFORE ‘r’ IS CALCULATED

COMPLETE EXERCISE 2E PG 85 Q’S 1-6COMPLETE EXERCISE 2F PG 88 Q’S 1-4

CLASSWORK/HOMEWORK