Sampling Techniques

Question 1

what is an opportunity sample?

Answer 1

sample produced by selecting people who are most easily available at the time of the study

Question 2

what are the pros and cons of opportunity samples?

Answer 2

pro: easy because can use the first participants found, means it takes less time

con: biased because sample is drawn from a small part of the target population

Question 3

what is a random sample?

Answer 3

sample produced by using a random technique such that every member of the target population has an equal chance of being chosen (e.g. random number generator)

Question 4

what are pros and cons of random samples?

Answer 4

pro: unbiased, all members of the target population have an equal chance of being chosen (however may end up biased as not all identified participants may agree to participate)

con: takes more time and effort than other methods because you need to obtain a list of all members of your target population, identify the sample then contact them to see if they wish to take part

Question 5

what is a volunteer (self-selected) sample?

Answer 5

a sample of participants produced by asking for volunteers

Question 6

what are pros and cons of a self selected sample?

Answer 6

pro: convenient way to find willing participants who are committed

pro: less likely to have participants drop out as they volunteered

con: sample biased as volunteers more likely to be more highly motivated and/or with extra time on their hands - they all share a common characteristic (volunteer bias)

Question 7

what is snowball sampling?

Answer 7

sampling that relies on referrals from initial participants to generate additional participants

Question 8

what are pros and cons of snowball sampling?

Answer 8

pro: enables researchers to locate groups of people who are difficult to access (e.g. drug addicts - once you have one you can get their friends)

con: sample is not likely to be a good cross-section from the population because it is friends of friends