1. Handling data: scattergraphs
BTEOTSSSBAT
Draw and interpret scattergraphs

3. Correlation
There are three types of correlation: positive, zero and negative.
Positive Zero Negative

4. Strong, moderate and weak correlation
The correlation can also be strong, moderate or weak.
The diagrams below give examples of each for a negative correlation:
Strong Moderate Weak

5. Example
A class sat two maths tests on one algebra and another on handling data.
The results are shown below: Algebra Handling
data
67 52
76 56
78 72
93 84
65 43
61 78
56 67
38 34
54 62
72 77
84 84
To draw the line of best fit we must first plot
the data on a scattergraph and then draw
the line of best fit by eye.

6. Which is the harder paper?
100
90
Algebra score 80
70
60
50
40
30
20
10
0
0 20 40 60 80 100
Handling
If someone scores 80 on the
data score
handling data how many marks
would they get on the algebra
paper?

7. Now try these
The scatter graph shows the height and mass of students.
Draw a line of best fit on the graph.
Use the line of best fit to estimate the height of someone who
has a mass of 60 kg.
80
mass/kg
70
60
50
40
140 145 150 155 160 165 170 175 180
height/ cm

8. What’s going on here? Do lemons cause accidents?