Chapter 1

Question 1

What is population?

Answer 1

The whole set of items that are of interest

Question 2

What is a census?

Answer 2

A study that observes/measures every member of the 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 are sampling units?

Answer 4

Individual units of a population.

Question 5

What is a sample frame?

Answer 5

A list formed by sampling units of a population are individually named or numbered.

Question 6

What is 1 advantage of a census?

Answer 6

It should give completely accurate results.

Question 7

What are 3 disadvantages of a cencus?

Answer 7

• Time consuming and expensive
• Can not be used when testing process involves destruction
• Large volume of data to process

Question 8

What are 3 advantages to sampling?

Answer 8

• Cheaper
• Quicker
• Less data to process

Question 9

What are 2 disadvantages of sampling?

Answer 9

• Data may not be accurate
• Data may not be large enough to represent small sub-groups

Question 10

What does random sampling allow?

Answer 10

Allows every member of the population to have an equal chance of being selected (removes bias).

Question 11

What is simple random sampling?

Answer 11

Every sample of size n is one where every sample of size n has an equal chance of being selected.

Question 12

What is systematic sampling?

Answer 12

Required elements are chosen at regular intervals from an ordered list. Only truly random if first number is chosen randomly.

Question 13

What is stratified sampling?

Answer 13

The population is divided into mutually exclusive strata and a random sample is taken from each.

Question 14

What is a stratum?

Answer 14

A subset (part) of the population which is being sampled.

Question 15

How do you calculate the number sampled in a stratum?

Answer 15

= (number in stratum / number in population) x overall sample size

Question 16

What are 4 advantages of simple random sampling?

Answer 16

• Unbiased
• Each member of the population has the same chance of being chosen
• Easy and cheap to implement for small populations
• Data from a random sample can be used in statistical calculation

Question 17

What are 2 disadvantages of simple random sampling?

Answer 17

• A sampling frame is needed
• The sample may not be representative of all sections of the population

Question 18

What are 3 advantages of systematic sampling?

Answer 18

• Unbiased
• Each member of the population has the same chance of being chosen
• Usually easy to carry out

Question 19

What is 1 disadvantage of systematic sampling?

Answer 19

• A sampling frame is needed, unless the population appears in a sequence like items on a production line.

Question 20

What is quota sampling?

Answer 20

When the researcher selects a sample that reflects the characteristics of the whole population.

Question 21

What is opportunity sampling?

Answer 21

Taking the sample from people who are available at the time the study is carried out and who fits the criteria you are looking for.

Question 22

What are 2 advantages of quota sampling?

Answer 22

• No sampling frame is needed
• Each section of the population is fairly represented

Question 23

What is 1 disadvantage of quota sampling?

Answer 23

• can introduce bias.

Question 24

What are 2 advantages of opportunity sampling?

Answer 24

• No sampling frame is needed
• Easy and cheap to carry out

Question 25

What are 3 disadvantages of opportunity sampling?

Answer 25

• May introduce bias
• Unlikely to produce a representative sample
• Highly dependent on individual researcher

Question 26

What are qualitative variables?

Answer 26

Non-numerical variables.

Question 27

What are quantitative variables?

Answer 27

Numerical variables

Question 28

What is a discrete variable?

Answer 28

can only take certain values (like number of people or shoe size) - this means there are ‘gaps’ between possible values.

Question 29

What is a continuous variable?

Answer 29

Can take any value within a particular range (like height or mass) - this means there are no gaps between possible values.