Year 1 Chapter 1

Question 1

What is a population

Answer 1

The whole set of items that are of interest.

Question 2

What is a census

Answer 2

Observes or measures 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 are advantages of a census

Answer 4

It should give a completely accurate result

Question 5

What are advantages of a sample

Answer 5

Less time consuming & expensive than a census

Fewer people have to respond

Less data to process than in a census

Question 6

What are disadvantages of census

Answer 6

Time consuming & expensive

Cannot be used when the testing process destroys the item

Hard to process large quantity of data

Question 7

What are disadvantages of sample

Answer 7

Data might not be as accurate

Sample may not be large enough to give information about small subunit groups of the population

Question 8

What is a sampling unit

Answer 8

Individual units of a population

Question 9

What is a sampling frame

Answer 9

Sampling units of a population are individually named or numbered to form a list

Question 10

What are 3 methods of random sampling

Answer 10

Simple

Systematic

Stratified

Question 11

What is a simple random sample

Answer 11

Size n

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

Question 12

What is lottery sampling

Answer 12

The members of sampling frame could be written on tickets and placed into a ‘hat’

Required number of tickets are drawn out

Question 13

What are 2 method of choosing numbers randomly

Answer 13

Random number generator

Lottery sampling

Question 14

What is systematic sampling

Answer 14

Required elements are chosen at regular intervals from an ordered list

E.g.

sample size 20 required from population of 100
Do 100/20=5 so take every 5th person

Question 15

What is a stratified sample

Answer 15

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

Question 16

Equation to work out the number sampled in a stratum

Answer 16

Number in stratum
——————————— x overall sample size
Number in population

Question 17

What are advantages of simple random sampling

Answer 17

Free of bias

Easy & cheap to implement for small populations and small samples

Each sampling unit has a known and equal chance of selection

Question 18

What are disadvantages of simple random sampling

Answer 18

Not suitable when population size / sample size is larger as its potentially time consuming, disruptive and expensive

Sampling frame is needed

Question 19

Advantages of systematic sampling

Answer 19

Simple and quick to use

Suitable for larger samples and large populations

Question 20

Disadvantages of systematic sampling

Answer 20

Sampling frame needed

Can introduce bias if sampling frame isn’t random

Question 21

Advantages of stratified sampling

Answer 21

Sample accurately reflects population structure

Guarantees proportional representation of groups within a population

Question 22

Disadvantages of stratified sampling

Answer 22

Population must be clearly classified into distinct strata

Selection within each stratum suffers from same disadvantages as simple random sampling

Question 23

What are 2 types of non-random sampling

Answer 23

Quota

Oppurtunity

Question 24

What is quota sampling

Answer 24

Interviewer/researcher selects a sample that reflects characteristics of the whole population

Question 25

What is opportunity sampling

Answer 25

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

Question 26

Advantages of quota sampling

Answer 26

Allows sample to still be representative of population

No sampling frame required

Quick

Easy

Inexpensive

Allows for easy comparison between different groups within a population

Question 27

Disadvantages of quota sampling

Answer 27

can introduce bias

Population must be divided into groups, which can be costly or inaccurate

• Increasing scope of study increases number of groups, which adds time and expense

• Non-responses are not recorded as such

Question 28

Advantages of opportunity sampling

Answer 28

Easy to carry out

Inexpensive

Question 29

Disadvantages of opportunity sampling

Answer 29

Unlikely to provide a representative sample

Highly dependent on individual researcher

Question 30

What is quantitative variables/data

Answer 30

Variables or data associated with numerical observations

Question 31

What is qualitative data/variables

Answer 31

Variables/data associated with non-numerical observations

Question 32

What’s a continuous variable

Answer 32

A variable that can take any value in a given range

Question 33

What’s a discrete variable

Answer 33

Variable that can take only specific values in a given range