Psychology - Research Methods - Sampling and Pilot Studies Flashcards
What do psychological studies involve?
Samples from a larger population
Target population
the entire group about which a researcher would like to be able to generalise their results to
What should a sample be?
representative of the population
Random sampling
When every member of the target population have the same chance of being selected
What are the advantages of random sampling?
No researcher bias - Maximise representativeness - Can generalise from sample to population
What are the disadvantages of random sampling?
Difficult to get full details of a target population - Not all members will be willing to take part, reducing sample
Systematic sampling
Participants selected by taking every Nth person from a list
What are the advantages of systematic sampling?
More simple that random sampling
What are the disadvantages of systematic sampling?
Process of selection can interact with a hidden periodic trait in the population making it no longer random - Not all members may want to take part making it unrepresentative
Stratified sampling
Classifying the population into categories and then randomly choosing a sample consisting participants from each category in the same proportion as they are in the population
Strata
How groups are divided by characteristics
What are the advantages of stratified sampling?
All groups within a population are included so it will be representative
What are the disadvantages of stratified sampling
Time consuming to get target sample - Some people can not be classified to sample - Complete representation is not possible
Opportunity sampling
A sample of participants produced by selecting people who are most easily available at the time of the study.
What is the advantage of opportunity sampling?
Easiest and most practical method of ensuring large samples when compared to stratified sampling which may be time consuming and expensive
What are the disadvantages of opportunity sampling?
There is a high chance the sample will not be representative and may be unethical
What is volunteer sampling?
involves people volunteering to participate in a study
What are the advantages of volunteer sampling?
Saves time and effort as they just need to make an advert and wait for participants
What are the disadvantages of volunteer sampling?
A certain type of person tends to volunteer and may be unrepresentative (volunteer bias)
What is a pilot study?
An initial run through of procedures used in an investigation, involving selecting a few people and trying the study. Can save time and money
What can a pilot study help spot?
any ambiguities or confusion in info given to participants or problems with the tasks given
floor effect
When a task is too hard, all performances are low as none of them can complete it
ceiling effect
When the task is so easy that all achieve virtually full marks and are “hitting the ceiling”
What is important to check in self-report pilot studies?
- The participants understand the questions - suitable options for closed questions - whether open questions are needed - whether the reporting method is appropriate
What is important to check in observation pilot studies?
- Observers agree on operational definitions - Inter-observer reliability - Behavioural categories are clear - whether behaviour is affected by observers
