Sampling

Question 1

5 types of sampling techniques

Answer 1

Random
Systematic
Stratified
Opportunity
Volunteer

Question 2

Random sample

Answer 2

Every person in target population has an equal chance of being selected

By using a lottery method - all members of target population are given a number and placed in a randomiser

Question 3

Advantage of random sample + explain

Answer 3

Potentially unbiased which means confounding variable/ extraneous variables are controlled

Enhances internal validity

Question 4

Disadvantage of random sample + explain

Answer 4

Time consuming and may not work due to a complete list of population is hard to get

Also some participants may refuse to take part

Question 5

Systematic sample

Answer 5

Participants are selected using a ‘set’ pattern (sampling frame) e.g alphabetical order

Every nth person is selected from a list of the target population

Question 6

Advantage of systematic sample + explain

Answer 6

Unbiased because the first item is usually selected at random - objective method

Question 7

Disadvantage of systematic sample + explain

Answer 7

Time and effort - a complete list of the population is required meaning we may as well use random sampling

Question 8

Stratified sample

Answer 8

Sample reflects proportions of people in certain subgroups within a population.

Subgroups are identified e.g gender or age groups. The relative percentages of the subgroups in the population are reflected in the sample

Question 9

Advantage of stratified sample + explain

Answer 9

Representative method - the characteristics of the target population are represented

Generalisability more likely than other methods

Question 10

Disadvantage of stratified sample + explain

Answer 10

Stratification is not perfect - strata cannot reflect all the ways in which people are different

Complete representation is not possible

Question 11

Opportunity sample

Answer 11

People who are simply most available i.e the ones who are nearest/easiest to obtain

By asking people nearby

Question 12

Advantage of opportunity sample + explain

Answer 12

Quick method - it is convenient because you just make use of the people who are closest

This makes it cheaper and one of the most popular sampling methods

Question 13

Disadvantage of opportunity sample + explain

Answer 13

Inevitably bias - sample is unrepresentative of the target population as it is drawn from a very specific areas such as one street in one town

This means that the findings cannot be generalised

Question 14

Volunteer sample

Answer 14

Participants select themselves

By advertising e.g place an advert in a newspaper or ask people to put hand up to a volunteer

Question 15

Advantage of volunteer sample + explain

Answer 15

Participants are willing - participants have selected themselves and know how much time and effort is involved

Likely to engage more than people stopped in the street

Question 16

Disadvantage of volunteer sample + explain

Answer 16

Volunteer bias - participants may share certain traits e.g want to be helpful

Respond to cues and generalisation limited