Sampling techniques and pilot studies

Question 1

what is a sample?

Answer 1

name given to the group of participants used in research

Question 2

what is the target population?

Answer 2

everybody your research is meant to represent

Question 3

what is a sampling frame?

Answer 3

a list of all the people forming a population from which a sample is taken

Question 4

what is sample called if it is not representative?

Answer 4

biased

Question 5

what are the 5 methods of choosing a sample?

Answer 5

-random sampling
-opportunity sampling
-stratified sampling
-self-selected or volunteer sampling
-systematic sampling

Question 6

what is random sampling?

Answer 6

when every member of the target population has equal chance of being selected

Question 7

explain briefly how random sampling works?

Answer 7

allocate each person of the target population a number and ask a random number generator to choose 100 numbers- the names against these numbers are the sample

Question 8

what are strengths of random sampling?

Answer 8

-everybody has equal chance of being drawn
-avoids researcher bias

Question 9

what are limitations of random sampling?

Answer 9

-requires access to all members of the target population (sampling frame)
-participants selected may not be willing to take part
-may produce sample which is unrepresentative of the target population

Question 10

what is stratified sampling?

Answer 10

when the sample is manipulated to represent the target population. Important characteristics of the target population are listed and the sample is chosen that will represent each of these characteristics

Question 11

what is the method for stratified sampling?

Answer 11

1. divide target population into sub categories
2. work out the proportion of each category needed in the sample
3. select the number from each group using a random number generator (random sampling)

Question 12

what are the strengths of of stratified sampling?

Answer 12

-representative of the target population
-avoids researcher bias

Question 13

what are the limitations of stratified sampling?

Answer 13

-time consuming and costly
-requires access to all members of the target population (sampling frame)
-participants selected may not be willing to take part

Question 14

what is an opportunity sample?

Answer 14

involves using participants who are easily available to the researcher

Question 15

what are the strengths of opportunity sampling?

Answer 15

-easy to do and not time consuming

Question 16

what are limitations of opportunity sampling?

Answer 16

-likely to produce a biased sample with similar characteristics
-participants selected may not be willing to take part
-sample may be unrepresentative of the target pop
-researcher bias

Question 17

what is volunteer or self selected sampling?

Answer 17

participants put themselves forward to take part, usually in response to an advertisement

Question 18

what are strengths of volunteer sampling?

Answer 18

-participants keen to take part

Question 19

what are limitations of volunteer sampling?

Answer 19

-likely to produce a biased sample with similar characteristics
-volunteer bias
-may produce a sample which is unrepresentative of target population
-researcher bias

Question 20

what is systematic sampling?

Answer 20

when every nth member of the target population is used

Question 21

how is systematic sampling carried out?

Answer 21

a sampling frame is needed and the ‘system’ is used to choose the sample (e.g. every 3rd person)

Question 22

what are strengths of systematic sampling?

Answer 22

-avoids researcher bias

Question 23

what are limitations of systematic sampling?

Answer 23

-requires access to members of the target population
-participants selected may not be willing to take part
-may produce a sample which is unrepresentative of the target population

Question 24

what is generalisation?

Answer 24

the extent to which findings from a particular study can be broadly applied to the pop.

Question 25

what is bias?

Answer 25

when certain groups may be over or under-represented in the sample selected- which will affect how far results can be generalised

Question 26

what is volunteer bias?

Answer 26

asking for volunteers may attract a certain type of person- which will affect how far results can be generalised

Question 27

what is a pilot study?

Answer 27

a small scale run of the actual investigation to check that the process runs smoothly and see if any changes need to be made -it usually involves fewer participants than the main study

Question 28

what sort of things are checked in a pilot study?

Answer 28

- have the participants fully understood the task (are the instructions clear?) -have they been given enough time for the task? -are materials used clear and appropriate? e.g. in a memory study this may be a word list -in an observation are the behavioural categories clear? -in an interview or questionnaire, are the questions clear? are there too many/ few? do changes need to be made?