Lesson starter: types of correlation

Scatter graphs Sunday, May 14, 2023

A scatter graph is used to try to find a relationship between two variables (things)

Here is an example of how the information about AGE and AMOUNT OF MONEY SPENT AT THE WEEKEND is put onto a scatter graph.

People were asked:

What is your age?

How much money did you spend this weekend?

Their answers were recorded in a table like this:

I’m 18 and I spent £25

Age 18 16

Amount 25 10

I’m 16 and I spent £10

Age 18 16 17 15 18

Amount 25 10 22 8 10

I’m 18 and I spent £10

I’m 17 and I spent £22

I’m 15 and I

spent £8

Age 18 16 17 15 18 17 19

Amount 25 10 22 8 10 15 30

I’m 17 and I

spent £15

I’m 19 and I spent £30

Age 18 16 17 15 18 17 19

Amount 25 10 22 8 10 15 30

Age - Amount Spent

05

101520253035

0 5 10 15 20

Age

Am

ount

Spe

nt

Age - Amount Spent

05

101520253035

0 5 10 15 20

Age

Am

ount

Spe

ntThis line is called the line of best fit. If it goes up in this direction, it has a positive correlation.

Age - Amount Spent

05

101520253035

0 5 10 15 20

Age

Am

ount

Spe

ntAge 18 16 17 15 18 17 19

Amount 25 10 22 8 10 15 30

 

1.Plot these points on a scatter diagram.

Pupil A B C D E F G H I J K L M

Shoe S. 2 2 3 4 5 7 6 5 6 7 4 3 2

Height 1.3 1.5 1.4 1.4 1.5 1.8 1.7 1.6 1.6 2 1.3 1.5 1.3

a.What type of correlation does the scatter graph show between shoe size and height? b.What can you usually say about a the connection between shoe size and height?

Plot these points on a scatter graph to show the connection between revision and number of GCSE passes.

Pupil A B C D E F G H I J K L

Hours Rev.

45 67 97 34 5 78 34 12 49 76 89 90

No. GCSE

4 6 9 1 0 5 2 1 5 8 9 10

a.Draw a line of best fit onto the scatter graph. b.Use this line to estimate how many hours are needed for 7 GCSE passes.