Sampling Flashcards
Target population
The group of people the experiment aims to find out about
Such as the average American or Brit etc
Sample
A group of people which aims to represent the target population as best as possible
Actual participants used in study
Sampling method
Ways of obtaining a sample in an experiment from the target population
4 sampling methods
Self selecting
Opportunity
Random
Snowball
Self selecting sample
When people volunteer to take part in the study
Done through advertising to participants who will contact researcher if they wish to take part
Opportunity sample
Participants produced by selecting who is most readily available to the researcher at the time (convenience)
Random sample
A technique where each member of the target population has an equal chance of being selected
Like drawing names from a hat
Snowball sample
Where participants will be asked to contact their friends and family to take part in research who will then ask their friends and family etc
Self selecting sample strengths
Participants consented to join the study so gained informed consent (ethics)
So less likely to withdraw and also more likely to cooperate
Self selecting sample weaknesses
May lack in terms of diversity: perhaps not enough people of certain backgrounds/jobs/ ethnicities didn’t volunteer or won’t include shy people
Cost of advertising
Might not get enough Ps in general
Opportunity sample strengths
Convenient and doesn’t include extra work of getting participants
Opportunity sample weaknesses
Biased/lacks in diversity based on where sample was randomly taken
Less ethical since participants will feel less prepared and perhaps obliged to continue
Random sample strengths
No bias from researcher since all had an equal chance of being selected
More representative therefore of target population since everyone had an equal chance of being selected
Random sample weaknesses
Participants may be less willing to participate if they were suddenly dropped into it
So more likely to withdraw causing bias in the sample
Difficult to get the whole total target population to have everyone be of equal chance to get picked
Snowball sample strengths
Less work for researchers since there will be less participants to acquire at first
Ps will convince more people to join if they ask family/friends themselves than if the researcher asked
Snowball sample weaknesses
Might be a bias in who participants will ask such as avoiding asking people who they think won’t score well so lacking in diversity w
Participants will share characteristics of who they ask so lacks in diversity
Small sample strengths and weaknesses
Easy to manage on a practical level for data and the experiment but not enough measurements will be taken to confirm a consistent effect across whole target population so less reliable
Large sample strengths and weaknesses
Hard to manage on a practical level but provides sufficient measurements to suggest a consistent effect
So more reliable
What does a sample need to be?
Representative of the target population so findings can be generalised to the whole population
Cost + time effective
Biased sample
A sample that doesn’t represent the target population or people in general
Gender bias
If a sample has majority male or female, it will have a gender bias
Androcentric = bias by mainly studying males
Age bias
If certain age ranges are omitted, the sample is not representative of all people eg only using students
Culture bias
By representing only 1 culture or country, the generalisability to other countries is low
When is a sample biased?
The sample is not diverse in terms of age/gender/ethnicity/culture/background
The sample was acquired by self select so may be biased in favour of including helpful people
Allowing people to withdraw may bias the sample is only include those who performed well
