sampling

Question 1

what is a sample?

Answer 1

the people the researcher actively uses in the research
group of people who take part in your research investigation. the sample is drawn from a target population and is presumed to be representative of that population

Question 2

what is a population?

Answer 2

the population is the group of people from whom the sample is drawn
we use a target population if we want to investigate specific individual differences

Question 3

what is a sampling frame?

Answer 3

a list of people in a target population organised into a certain order e.g: alphabetical order

Question 4

what are the 5 sampling types?

Answer 4

random
systematic
stratified
volunteer
opportunity

Question 5

what is random sampling?

Answer 5

each person has an equal chance of being selected

Question 6

outline how to carry out a random sample

Answer 6

• obtaining a complete list of all the names of the members in the target population.
• all of the members are assigned a number
• the actual sample is chosen by lottery method or something similar like using a computer, or picking numbers from a hat

Question 7

advantages of random sampling

Answer 7

• no researcher bias - no influence
• a random sample is potentially unbiased, any confounding or extraneous variables are equally divided between different groups. (increased internal validity)
• more likely to have a representative sample

Question 8

disadvantages of random sampling

Answer 8

• time consuming
• a complete list of the whole target population can be very difficult in large studies.
• still potentials for a sample that is less representative
• volunteer bias - selected participants may be unwilling to take part

Question 9

what is systematic sampling?

Answer 9

sample where every nth member of the target population is chosen. e.g: ever 3rd student in a register.
- then a sampling frame is chosen

Question 10

outline how to carry out a systematic sample

Question 11

advantages of systematic sampling

Answer 11

• it is objective
• no researcher bias - no influence
• fair representation of population

Question 12

disadvantages of systematic sampling

Answer 12

• time consuming
• participants could refuse to participate (results in a Volunteer sample)

Question 13

what is stratified sampling?

Answer 13

form of sampling where the make up of the sample reflects the proportions of people in certain subgroups within the target population

Question 14

outline how to carry out a stratified sample

Answer 14

• identify the strata
• calculate the required proportion for each stratum based on the size of the target population
• select the sample at random for each stratum
• to do this, you can use a random selection method e.g. using a computer

Question 15

advantages of stratified sampling

Answer 15

• no researcher bias - no influence
• produces a representative sample because its designed to reflect the make up of the target population
• generalisation of results is possible

Question 16

disadvantages of stratified sampling

Answer 16

• the identified strata cannot reflect all of the ways that people are different, complete representation is not possible
• participants could refuse to participate (results in a Volunteer sample)
• time consuming - identifying each strata and complying sampling frames

Question 17

what is volunteer sampling?

Answer 17

involves participants selecting themselves to be part of the sample.

Question 18

outline how to carry out a volunteer sample

Answer 18

• may put an advertisement in a newspaper or on a notice board of some kind

Question 19

advantages of volunteer sampling

Answer 19

• collecting the sample is easy
• less time consuming to gather
• ends up with participants who are more engaged

Question 20

disadvantages of volunteer sampling

Answer 20

• Volunteer bias : may attract a certain profile of person who is likely to try please the researcher meaning results are less generalisable - Hawthorne Effect
• motivations like money - may not be taken seriously

Question 21

what is opportunity sampling?

Answer 21

deciding to use anyone who is willing and available to help.
the researcher simply takes the chance to ask whoever is around at the time of the study
e.g: in the street or from students
this sample is used when the members of the target population and so difficult to obtain

Question 22

outline how to carry out an opportunity sample

Question 23

advantages of opportunity sampling

Answer 23

• is convenient
• method is much less costly in terms of money and time

Question 24

disadvantages of opportunity sampling

Answer 24

• suffers from two types of bias:
• sample is unrepresentative as is from a very specific area and therefore cannot be generalised
• researcher bias : the researcher has complete control over the selection of participants and could for example avoid people they don’t like the look of.