Sampling

Question 1

What is a population?

Answer 1

A group of individuals that a particular researcher may be interested in studying

Question 2

What is a sample?

Answer 2

• a group of people drawn from a target population and are representative of it that take part in a research investigation
• allows generalisation of findings to be possible

Question 3

What is generalisation?

Answer 3

The extent to which findings & conclusions can be broadly applied to the population

Question 4

What is bias?

Answer 4

• When certain groups are under or over-represented within the sample selected
• this limits the extent of generalisations that can be made

Question 5

What is a random sample?

Answer 5

• a form of sampling where all members of target population have an equal chance of being selected
• list of all members is first obtained and are all assigned numbers
• sample is generated through computer randomiser or out of hat

Question 6

What is a systematic sample?

Answer 6

• when every nth member of target population is selected
• sampling frame produced where list of people is organised into e.g. alphabetical order
• interval between members is random to reduce any bias

Question 7

What is a stratified sample?

Answer 7

• a form of sampling where composition of sample reflects proportions of people in certain sub-groups (strata) within target or wider population
• to carry out stratified sample the researcher identifies different strata that make up the population
• pps that make up each stratum are selected using random sampling

Question 8

What is an opportunity sample?

Answer 8

• since representative samples are hard to obtain some researchers decide to select anyone who is willing & available
• researcher takes chance to ask whoever is around at the time of study e.g. on the street

Question 9

What is a volunteer sample?

Answer 9

• involves pps selecting themselves to be part of the sample
• researcher may place an advert to select a volunteer sample

Question 10

Evaluation: Random sample

Answer 10

• free from researcher bias since they have no influence over who is selected and prevents them from picking people who may support their hypothesis
• is difficult & time-consuming to conduct since a complete list of all members in a target population is hard to obtain
• laws of probability suggest that a random sample is more representative than opportunity sampling
• selected pps may refuse to take part (applies to many sampling methods)

Question 11

Evaluation: Systematic sample

Answer 11

• avoid researcher bias since researcher has no influence over who is selected after selection system has been established
• usually fairly representative e.g. almost unlikely for all male sample through systematic sampling

Question 12

Evaluation: Stratified sample

Answer 12

• avoids researcher bias since it is beyond influence of researcher when target population has been sub-divided into strata
• produces representative data since it’s designed to accurately reflect composition of population
• identified strata can’t reflect the ways people are different so complete representation of target population is not possible

Question 13

Evaluation: Opportunity sample

Answer 13

• is convenient since it saves researcher a lot of time & effort and is less costly than random sampling for e.g.
• sample is unrepresentative of target population since its drawn from a specific area e.g. certain street
• findings can’t be generalised to target population
• researcher has complete control over who is selected so they may avoid certain people that don’t benefit them

Question 14

Evaluation: Volunteer sample

Answer 14

• requires minimal input from researcher so is less time-consuming compared to other forms of sampling
• volunteer bias is a problem since asking for volunteers may attract a certain group of people who are eager & curious
• this might affect how far findings can be generalised