Sampling Flashcards
The sample
People who are selected to take part in the experiment
Is seleted from a larger group, known as the target population.
We can generalise the findings for the target population
Different types of sampling techniques
Random sampling
Systematic sampling
Stratified sampling
Opportunity sampling
Volunteer sampling
Random sampling
Every member of the target population has an equal chance to be selected.
Evaluation of random sampling
(+) Potentially unbiased as everyone has an equal chance (-) but some may decline
(-) Takes more time and effort
Systematic sampling
Participant chosen by choosing every nth person
Uses a predetermined system to select participants
Evaluation of systematic sampling
(+) Not actively biased- selected using an objective system
(-) Nothing is truly unbiased only you use a random number generator- may be inheritly unrepresentative.
Stratified sampling
Chosen according to their frequency in the population
Subgroups in the population are identified
Participants are obtained from each subgroup in accordance to their frequency in the target population
Evaluation of stratified sampling
(+) Likely to be more representative as there is more representation of subgroups
(-) Each group may be biased in other ways.
Opportunity sampling
Selecting those who are most easily available at the time of the study.
E.G people who walk past on the street.
Evaluation of opportunity sampling
(+) Quick and easy
(-) May be biased due to the time and day and place it took place in.
Volunteer sampling
Produced by asking for volunteers to take part
E.G advertising in a newspaper
Evaluation of volunteer sampling
(+) Has access to a variety of participants - more representative
(+) Quick and easy
(-) Participants are more ‘keen’ to take part - may lead to volunteer bias
