Sampling techniques

Question 1

What is a population and what is a sample

Answer 1

Population - Group of people of interest (target population)

Sample - Specific part of the group of interest

Question 2

What is random sampling

Answer 2

Everyone has an equal chance of being chosen through:
Lottery method
Random number table
Random number generator

Question 3

Strengths and weaknesses of random sampling

Answer 3

Strengths:
Representative - Makes use of whole population
High population validity

Weaknesses:
Representativeness isn’t guaranteed

Question 4

What is stratified sampling

Answer 4

Population is split into strata

Specific number is taken from each strata to form sample using random sampling technique

Question 5

Strengths and weaknesses of stratified sampling

Answer 5

Strengths:
Representative - Uses whole population at first - high population validity

Weaknesses:
Time consuming

Question 6

What is systematic sampling

Answer 6

Uses predetermined system e.g. nth term

Question 7

Strengths and weaknesses of systematic sampling

Answer 7

Strengths:
Representative - Makes use of whole population - high population validity only if randomised beforehand

Weaknesses:
Can be unbiased

Question 8

What is opportunity sampling

Answer 8

Makes use of people available at the time

Question 9

Strengths and weaknesses of opportunity sampling

Answer 9

Strengths:
Quick and convenient - less planning/resources required

Weaknesses:
Unrepresentative - Doesn’t make use of the whole population

Question 10

What is volunteer sampling

Answer 10

People offer to take part

Question 11

Strengths and weaknesses of volunteer sampling

Answer 11

Strengths:
Quick and convenient- less planning/resources required

Weaknesses:
Unrepresentative - volunteer bias - Participants have a reason to take part