1. Objectives Recognise types of data Construct stem and leaf diagrams
Understand grouped frequency distributions
Construct cumulative frequency polygons

2. Types of Data Qualitative Quantitative Height Town of birth Age
Eye colour

3. Types of Data Continuous Discrete Time Cost in £’s Volume
Number of children
Height
Shoe size
Weight
Number of pets

4. Stem and Leaf Diagrams 35 23 1 2 3 4 1 2 3 4 6 7 5 8 9 8 6 7 3 5 2 7 7 7 9 8 5 3 7 1 2 1
means 18

5. Stem and Leaf Diagrams

6. Grouped frequency
A sample of the red cell count per 1mg of blood from visits made to the doctor by 150 patients, assume data is continuous

7. Class 5 - 9 7 4.5 5 9 9.5 midpoint lower class boundary
5 9
lower class limit
upper class limit
9.5
upper class boundary
class width

8. 25 50 75
100
125
150
175
4.5
9.5
14.5
19.5
24.5
29.5
34.5