sampling techniques

Question 1

what is opportunity sampling?

Answer 1

using whoever is immediately available

how - go out and accost passers-by

Question 2

what is volunteer sampling?

Answer 2

Use whoever puts themselves forward
how - advertise in the paper

Question 3

what is stratified sampling?

Answer 3

sampling technique where the researcher divides or ‘stratifies’ the target group into sections, each representing a characteristic that should be present in the final sample

participants selected in proportion to subgroup’s frequency in the target population

how - identify subgroups (e.g. age groups) and identify the number in each subgroup in the target population, and then select equivalent sample

Question 4

what is random sampling?

Answer 4

Every member of the target population has an equal chance of being selected

how - number everyone in the target popuilation, use a random number generator, or put the names in a hat and draw out required number of participants

Question 5

what is systematic sampling?

Answer 5

A systematic method is chosen for selecting from a target group

how - every fourth person in a list could be used in the sample.

Question 6

what are the strengths of using opportunity sampling?

Answer 6

• quicker and easier way of gaining a sample than other methods because participants are readily available

Question 7

what are weaknesses of using opportunity sampling?

Answer 7

• the sample may not be representative, since the people who happen to be in that one location may not have all the characteristics of the target population.
• as the researcher decides who to ask or not to take part in their study, this could result in researcher bias, meaining the researcher may select participants they feel are more likely to produce a preferred result

Question 8

what are the strengths of using volunteer sampling?

Answer 8

• advertising for participants can reach a very large number of potential participants, especially if the newspaper or website is widely read
• an easy sample to collect as participants are putting themselves forward rather than having to be found individually and contacted directly

Question 9

what are the weaknesses of using volunteer sampling?

Answer 9

• the sample may not be generalisable to the target population because of volunteer bias, the types of people who volunteer to take part are likely to have different characteristics to the target population, they are likely to be friendlier and have more free time available

Question 10

what are the strengths of using stratified sampling?

Answer 10

• the sample is represntative of the larger target population, meaning teh results found with the sample should be generalisable to the target population
• as the participants are randomly chosen from within each stratum this avoids researcher bias

Question 11

what are the weaknesses of using stratified sampling?

Answer 11

• not every possible characteristic can be included in the a stratified sample, and as the researcher decides which strata are important, this may result in bias
• it is time consuming to establish strata and then randomly select from each stratum

Question 12

what are the strengths of using random sampling?

Answer 12

a random sample avoids researcher bias as the researcher cannot choose the participants they want to form the sample, avoiding the possibility the researcher picks participants they feel are likely to give a preferred result

Question 13

what are the weaknesses of using random sampling?

Answer 13

• by chance participants could be picked that produce an unrepresentative sample, for example too few members of one gender or with no members of a minority group. which reduces generalisability
• it can be difficult and time-consuming to get a full list of a large target population