1. Data ?
Data is the information which you
have obtained(or have been given)
2. Types of Data
Data
Qualitative data Quantitative data
( non numerical, like colours) ( numerical, like no of people on a bus)
There are two types of Quantitative data
Continuous data Discrete data
3. Continuous Data
Discrete Data
• Continuous data is which could take all the
possible values within a given range,e.g the
height of a tree.
• Discrete data is which increases in steps( often
whole numbers),e.g. the numbers of rooms in
a building.
• Discrete data does not have to consist only whole numbers.
For example the size of shoes is also a discrete data, and the
sizes go up in halves.
4. Collecting Data
• Surveys
• Censuses
• Samples
We need to design and criticise questions
relating to Questionnaires
5. Qualitative or Quantitative
Continuous or Discrete
• The height of a person
Continuous
• The number of children in a family
Discrete
• The colour of the shoes of people on a train
Qualitative
• The speed of a car
Continuous
6. Questionnaires
• A questionnaire is a list of questions designed
to collect data. There are two types of
questions used in questionnaires
1. An open question is one that has no
suggested answers.
2. A closed question is one that has a set of
answers to choose from, usually in the form
of response boxes.
7. Questionnaires
• It is important that information in the
response boxes:
1. Does not overlap
2. Covers all possible answers
3. Relates to the questions
4. Be answered quickly
8. Questionnaires
• A small carefully chosen number of people can
be used to represent the population being
surveyed. These chosen individuals are called
a sample and investigation is called a sample
survey,
• The sample must be representative of all the
people being investigated. If it isn't, it is a
biased.
9. Example
Well designed questionnaire
1. Tick one box to indicate your age group
Under 21 21 to 30 31 to 40 41 to 50 Over 50
These are response boxes. The categories do not overlap
10. 2.How often have you visited the dentist in the
last 4 years? Tick one box
Never 1 or 2times 3 or 4 times 5 to 6 times More than 6 times
These options are specific, unlike often or sometimes
3. Do you agree or disagree that people who visit
dentist regularly have fewer fillings in their teeth?
11. 3. Do you agree or disagree that people who
visit dentist regularly have fewer fillings in
their teeth?
Agree Disagree
Agree and Disagree makes the question inbiased
12. Example
• Tom wants to find out how many DVDs people
buy. He uses this question on a questionnaire.
How many DVDs do you buy?
1-5 5-10 10-15 15-20
Write down three things wrong with this question.
• The response boxes overlap
• The response boxes do not cover all possible answers( 0 or more
than 20 DVDs)
• There is no time period in which the DVDs are bought,e.g each
week or each month.
13. Representing data
We can represent data in different ways.
1. Two way Tables
2. Pictograms
3. Bar charts
4. Frequency polygons
5. Pie charts
14. Averages and range
1. Mean, median, mode and range
2. Stem and leaf diagrams
3. Averages from table 1( discrete data)
4. Averages from table 2 ( continuous data)
5. Scatter graphs
15. Two -Way Tables
Year 7 Year 8 Year 9 Total
Vegetarian 14 22 25 61
Not vegetarian 72 63 54 189
Total 86 85 79 250
In total 250 students were
surveyed
86 Year 7
students
surveyed
61
vegetaria
n total
63 non-
vegetarian
in year 8
16. Worked Example
• The two way table shows some arrangement
of 85 students. Complete the two-way table
School
Lunch
Packed
Lunch
Others Total
Female 21 13 47
Male 5
Total 40 85
17. Answer -Worked Example
• The two way table shows some arrangement
of 85 students. Complete the two-way table
School
Lunch
Packed
Lunch
Others Total
Female 21 13 13 47
Male 19 5 14 38
Total 40 18 27 85
