COLLECTING and REPRESENTING DATA

Question 1

What are the two types of data

Answer 1

Quantitative and Qualitative

Question 2

What are the two types of Quantitative data?

Answer 2

Continuous and Discrete data

Question 3

Define qualitative data

Answer 3

non-numerical data such as type of car or colour of hair.

Question 4

Define quantitative data

Answer 4

numerical data such as measures of height or weight

Question 5

Define categorical data

Answer 5

Variables can be sorted into categories. Categorical
data is always qualitative.

Question 6

What is Bivariate data?

Answer 6

Bivariate data involves pairs of related data values, such as exam results and time spent
on study.

Question 7

What is multivariate data?

Answer 7

Multivariate data involves sets of three or more related data values, such as
age, height and weight.

Question 8

What is Primary data?

Answer 8

Primary data is information that you collect
yourself.
You could do an experiment, carry out a survey
or use a questionnaire to collect primary data.

Question 9

What is Secondary data

Answer 9

Secondary data comes from published sources,
such as newspapers, books or the internet.
You could take information from a table in a
magazine to collect secondary data.

Question 10

Sylvie wants to investigate whether a new type of medication helps people who have difficulty sleeping. She plans to run a laboratory experiment in a hospital with patients who suffer from
this condition.
Identify the explanatory and response variables in this experiment.

Answer 10

The explanatory variable is the type of medication.

The response variable is the degree of difficulty the patient has in sleeping.

Question 11

what is an outlier or anomalous value?

Answer 11

Values that does not fit the pattern of the rest of the data.

Question 12

Sylvie wants to investigate whether a new type of medication helps people who have difficulty sleeping. She plans to run a laboratory experiment in a hospital with patients who suffer from
this condition.
Describe one advantage and one disadvantage of doing this as a laboratory experiment.

Answer 12

An advantage is the medication can be controlled and the amount of sleep can
be measured.

A disadvantage is that the patient may experience difficulty in sleeping because they
are out of their home environment.

Question 13

Define population

Answer 13

A population is everything or everybody
that could possibly be involved in an
investigation, e.g. students in a school, all
the people who use the local gym.

Question 14

Define census

Answer 14

A census gathers data from the whole
population.

Question 15

Define sample

Answer 15

A sample gathers data from some of the
population.

Question 16

Define representative sample

Answer 16

A representative sample should contain
all the characteristics of the population to
avoid bias. A sample that is too small may
not represent the population and may bias
the results.

Question 17

Define sampling units

Answer 17

The sampling units are the people or items
that are to be sampled.

Question 18

Define Sampling frame

Answer 18

A sampling frame is a list of all the
members of the population from which the
sample will be taken.

Question 19

Define pilot survey

Answer 19

A pilot survey is a small sample analysed
first before any large-scale samples.

Question 20

Define pre-test

Answer 20

A pre-test is a pilot where questions for a
questionnaire are usually tried out.

Question 21

Define random sample

Answer 21

A random sample is one in which every member of the population has an equal chance of
being selected.

Question 22

What are the methods for random sampling?

Answer 22

Give each item in your sampling frame a unique number. To select the numbers for the items
in your sample, you can:
* use a random number table
* use a random number generator on a computer or calculator
* put the numbers of the items on pieces of paper and select at random from a hat
* roll sets of fair 10-sided dice to generate digits from 0 to 9.

Question 23

Advantages of random sampling

Answer 23

Random sample is more likely to be
representative of the population, provided
the sample is large enough.

Choice of members of sample is unbiased.

Question 24

Disadvantages of random sampling

Answer 24

A full list of the whole population is needed.

A large sample size is needed.

Question 25

Define stratified sampling

Answer 25

Stratified sampling can be used when the population can be split into distinct groups.

Question 26

What is a strata/stratum?

Answer 26

A stratum is a group in the population.
In a stratified sample, the relative sizes of the groups in the sample are the same as their relative sizes in the whole population.

Question 27

What is the formula to work the number of sample in each strata?

Answer 27

(stratum size/population size) x number in sample

Question 28

Define Judgement sampling

Answer 28

Judgement sampling uses judgement to select a sample that is representative of
the population.

Question 28

Define Opportunity sampling

Answer 28

Opportunity sampling uses the people (or objects) that are available at the time.

Question 29

Define Cluster sampling

Answer 29

Cluster sampling can be used when the population is in groups. A random sample
of these groups is selected and all items in the selected groups are included in
the sample.

Question 30

Define Quota sampling

Answer 30

Quota sampling involves splitting the population into groups with certain
characteristics (e.g. age, gender) and selecting a given number from each group.
For example, a market researcher might ask 10 adults and 10 children about their reaction to the 2018 GCSE results.

Question 31

Define Systematic sampling

Answer 31

In systematic sampling, items are selected from the population at regular intervals either in time or in space. For example, every 5th car that passes a location or every 3rd house on a street.

Question 32

What is a questionnaire?

Answer 32

A questionnaire is a set of questions designed to collect primary data.

Question 33

What are the advantages of questionnaire?

Answer 33

• Much cheaper to do
• Each person answering the question is
  treated in the same way

Question 34

What are the disadvantages of questionnaire?

Answer 34

• Can be inflexible
• People may misunderstand
  some questions

Question 35

What are the golden rules for designing a questionnaire? Hint: There are five golden rules

Answer 35

✓ Make questions clear and closed.
✓ Avoid open questions.
✓ Don’t ask leading questions.
✓ Have response boxes which are
unambiguous.
✓ Have response boxes which cover all
possible replies and don’t overlap.

Question 36

What is a hypothesis?

Answer 36

A hypothesis is a precise statement about something you can measure that can be tested by collecting and analysing data.

Question 37

Rosa wants to investigate the amount of time
male and female students spend using their
mobile phones each day.
(a) Write a hypothesis Rosa could use.

Answer 37

Female students spend more time on their mobile phones than male students.

Question 38

What is a Choropleth map?

Answer 38

A choropleth map uses different colours or shading to show how data varies across different geographic areas.

Question 39

What are the three types of Skewness?

Answer 39

Positive Skew: Most of the data values are at the
lower end and the distribution is
stretched out in the positive
direction.

Symmetrical: The distribution is symmetrical about the middle and has no skew.

Negative Skew: Most of the data values are at the
upper end and the distribution is stretched out in the negative
direction

Question 40

What are the things to watch for in misleading diagrams?

Answer 40

• vertical scales that are too big or too small, are not linear or do not start at zero
• axes that are not labelled clearly
• missing features, such as a key
• 3D diagrams, which may distort the features.