sampling techniques

Question 1

sampling techniques definition

Answer 1

the method used to select people from the population

Question 2

sample definition

Answer 2

a group of people who take part in a research investigation. The sample is drawn from a target population and is presumed to be representative of that population

Question 3

population definition

Answer 3

a group of people that are the focus of the researcher’s interest, from which a smaller sample is drawn

Question 4

volunteer sample

Answer 4

involves participants selecting themselves to be part of the sample

Question 5

volunteer sample strengths

Answer 5

• collecting it is easy as it requires minimal input from the researcher so less time consuming
• researcher ends up with more engaged participants

Question 6

volunteer sample weaknesses

Answer 6

• volunteer bias is a problem as asking for volunteers may attract a certain profile of person (one that is more curious and likely to please the researcher which affects generalisation)

Question 7

opportunity sample

Answer 7

researchers select anyone who happens to be willing and available

Question 8

opportunity sample strengths

Answer 8

• convenient
• less time consuming
• more economical
• list of target population is not required so there is no need to divide the population

Question 9

opportunity sample weaknesses

Answer 9

• has 2 forms of bias
• sample is unrepresentative of the target population as it is drawn from a specific area so findings cannot be generalised to the target population
• the researcher has control over the selection of participants so may avoid some people

Question 10

random sample

Answer 10

sophisticated form of sampling in which all members of the target population have an equal chance of being selected

Question 11

random sample strengths

Answer 11

• potentially unbiased as EVs and CVs are equally divided between different groups

Question 12

random sample weaknesses

Answer 12

• difficult and time-consuming to conduct as a complete list of target population may be difficult to obtain
• may end up with a sample that is still unrepresentative
• selected participants may refuse to take part

Question 13

stratified sample

Answer 13

sophisticated form of sampling in which the composition of the sample reflects the proportions of people in certain subgroups within the target population

Question 14

how to carry out a stratified sample

Answer 14

• identify the strata (subgroups) in the target population
• calculate the proportions of the target population that each strata represents
• select the calculated number of people needed from each strata randomly so the sample represents the population

Question 15

stratified sample strengths

Answer 15

• produces a representative sample because it is designed to accurately reflect the composition of the population so generalisation of findings is possible

Question 16

stratified sample weaknesses

Answer 16

• identified strata cannot reflect all the ways that people are different, so complete representation of target population is not possible

Question 17

systematic sample

Answer 17

when every nth member of the target population is selected

Question 18

systematic sample strengths

Answer 18

• avoids bias because member selection happens through the use of a sampling interval (as long as interval and starting place is chosen randomly)
• objective because once the system for selection is established, researcher has no influence over who is chosen

Question 19

systematic sample weaknesses

Answer 19

• time consuming
• participants may refuse to take part
• sample is not representative as every nth member may be a male for example

Question 20

bias

Answer 20

when certain groups are over or under represented within the sample selected. This limits the extent to which the generalisations can be made to the target population

Question 21

generalisation

Answer 21

the extent to which findings and conclusions from a particular investigation can be broadly applied to the population. This is possible if the sample of participants is representative of the target populaton

Question 22

how to conduct a random sample

Answer 22

• researcher obtains list of names of target population
• allocate them all a different number
• use a random number generator to randomly select 20 numbers
• numbers converted back to names and these are the 20 participants