Sampling Techniques

• Where participants in the target population has the same and equal chance of being selected
• Without any bias from the psychologist
• 'Lottery Method'

Advantages

• Likely to be the most representative in theory because of the equal chance and being without bias

Disadvantages

• Difficult to achieve as everyone in the target population needs to be know
• This means that it is rarely used
• Also it may still be unrepresentative in practice .e.g. all females

• Participants are selected according to availability
• Using people who happen to be around at the time .e.g. students in the library

Advantages

• Are more convenient
• Less time consuming and less costly
• This means they are frequently used

Disadvantages

• Likely to be unrepresentative as it is drawn from one specific location
• May share similar characteristics .e.g. IQ and age
• Could be bias as it is difficult to generalise
• Also the researcher is in control over the selection so may just approach people they like the look of

• Participants self-selecting themselves to participate
• Coming forward in responce to a request

Advantages

• More convenient
• Less time consuming
• This means it is frequently used

Disadvantages

• Likely to be unrepresentative of the population
• May share similar characteristics .e.g. more free time or more willing
• Difficult to generalise

• Devising a sampling frame (a list of people) and then selecting every nth person
• E.g. Selecting every 3rd house on a street

Advantages

• Avoids researcher bias
• Researcher has no influence over which participants are being selected
• Can be objectively generalised to target population

Disadvantages

• Possible that the sample is unrepresentative
• Should equally represent all members but may not in practice
• May be a 'hidden trait' .e.g. every 5th house may have a child under the age of two
• Difficult to generalise

• Complex form of identifying different sub groups (strata) which make up a target population
• Then selecting participants from each group randomly
• Sample size / Target population x size of group

Advantages

• Avoids researcher bias as they have no influence
• Finding can be objectively generalised

Disadvantages

• Requires a full list of the population and having an awareness of which strata each person falls into
• Extremely time consuming