Chapter 1: Data Collection

Question 1

What is a population?

Answer 1

The whole set of items that are of interest to you that you wish to sample

Question 2

What is a census?

Answer 2

A measure of every member of a population

Question 3

What is a sample?

Answer 3

A selection of observations taken from a subset of the population which is used to find out information about the population as a whole

Question 4

What is a sampling unit?

Answer 4

Individual units of a population

Question 5

What is a sampling frame?

Answer 5

Sampling units which are numbered to form a list

Question 6

What is an advantage of a census?

Answer 6

It will give a completely accurate result as you are questioning everyone

Question 7

What is are 3 disadvantages of a census?

Answer 7

• Time Consuming
• Expensive
• Cannot be used when the testing involves destroying the items

Question 8

What are 3 advantages of a sample?

Answer 8

• Less time consuming and expensive than a census
• Fewer people have to respond
• Less data to be processed than a census

Question 9

What are 2 disadvantages of a census?

Answer 9

• The data may not be accurate
• The sample may not be large enough to give information about small subgroups of the population

Question 10

What is a simple random sample?

Answer 10

Where every size of n has an equal chance of being selected

Question 11

What is systematic sampling?

Answer 11

The elements are chosen at regular intervals eg every 5th person is chosen

Question 12

What is stratified sampling?

Answer 12

The population is divided into mutually exclusive strata and a sample is taken from each eg they are split into males and females and then 20 people from each is taken

Question 13

What are 3 advantages of simple random sampling?

Answer 13

• Free of bias
• Easy and cheap to use for small samples
• Each sample unit has an equal chance of being selected

Question 14

What are 2 disadvantages of simple random sampling?

Answer 14

• Not suitable when the population size is large as it may be time consuming and expensive
• A sampling frame is needed

Question 15

What are 2 advantages of systematic sampling?

Answer 15

• Simple and quick to use
• Suitable for large samples ad populations

Question 16

What are 2 disadvantages of systematic sampling?

Answer 16

• A sampling frame is needed
• It can introduce bias if the sampling frame is not random

Question 17

What are 2 advantages of stratified sampling?

Answer 17

• Sample accurately reflects the population structure
• Guarantees accurate representation of groups in a population

Question 18

What are 2 disadvantages of stratified sampling?

Answer 18

• Population must be clearly classified into a distinct strata
• Selection within each stratum suffers from the same disadvantages as simple random sampling

Question 19

What are the 2 types of non-random sampling?

Answer 19

• Quota sampling
• Opportunity sampling

Question 20

What is quota sampling?

Answer 20

An interviewer selects a sample that reflects the characteristics of the whole population eg they will look for people aged 21-30, 30-40 and then ask them the question

Question 21

What is opportunity sampling?

Answer 21

Taking a sample from people who are available at the time the study is carried out eg you stand outside a supermarket and ask people to take your survey

Question 22

What are 4 advantages of quota sampling?

Answer 22

• Allows a small sample size to still be representative of the population
• No sampling frame required
• Quick, easy and inexpensive
• Allows for easy comparison between different groups

Question 23

What are 4 disadvantages of quota sampling?

Answer 23

• Non-random sampling can introduce
• Population must be divided into groups which can be costly and inaccurate
• Increasing scope of study increases number of groups which adds time and expense
• Non-responses are not recorded as such

Question 24

What are 2 advantages of opportunity sampling?

Answer 24

• Easy to carry out
• Inexpensive

Question 25

What are 2 disadvantages of opportunity sampling?

Answer 25

• Unlikely to provide a representative
• Highly dependent on individual researcher

Question 26

What is quantitive data?

Answer 26

Data with numerical values

Question 27

What is qualitative data?

Answer 27

Data with non-numerical values

Question 28

What is continuous data?

Answer 28

A variable that can take any value eg time can be 2 seconds, 2.1 seconds, 2.01 seconds

Question 29

What is discrete data?

Answer 29

A variable that can’t take any value eg hair colour