2.3.1 Participants & Probability sampling

Question 1

what is a target population?

Answer 1

a group of people sharing a set of characteristics about which the researcher wishes to draw conclusions

Question 2

in a study to investigate whether children aged 5 - 11 watch to much tv who is the target population?

Answer 2

children aged 5 - 11

Question 3

in an ideal world who would you study?

Answer 3

everyone in your target population

Question 4

why is it not possible to carry out research on everyone in your target population?

Answer 4

target population is often too large

Question 5

instead of studying the entire population who do we look at?

Answer 5

a small representative sample

Question 6

why is it important the sample is representative of the target population?

Answer 6

do it is a true reflection and you are able to generalise

Question 7

when deciding sample size what do you need to consider?

Answer 7

time
money
resources

Question 8

what is sampling?

Answer 8

how participants are selected for research studies

Question 9

what is probability sampling?

Answer 9

all the individuals in the target population have an equal chance of being selected

Question 10

what is a sampling frame?

Answer 10

a complete list of the target population from which you can draw your sample

Question 11

give examples of sampling frames:

Answer 11

registers - school, work, births, marriages
medical records
phonebooks
gym membership
DVLA list

Question 12

what is random sampling?

Answer 12

each person in a given population stands an equal chance of being selected

Question 13

what is a strength of random sampling?

Answer 13

laws of probability predict it is the best chance of gaining a representative sample

Question 14

one weakness of random sampling is that a representative sample isn’t guaranteed, why?

Answer 14

accidental bias - e.g. all boys selected

Question 15

weaknesses of random sampling - what three reasons can make it hard to obtain a random sample?

Answer 15

1. cant get a list of everyone in target population
2. cant contact everyone randomly selected
3. those selected may refuse to participate

Question 16

what is systematic random sampling?

Answer 16

researcher randomly selects the first participant in the population and then selects each nth participant from the list

Question 17

what is stratified sampling?

Answer 17

target population divided into sub categories

participants randomly selected within each sub category in the proportion they occur in the population

Question 18

(stratified sampling) if 2.5% of British people are of Indian origin, how many in your sample will be randomly selected from people of British Indian origin?

Answer 18

2.5%

Question 19

what is the most representative probability sampling method?

Answer 19

stratified sampling

Question 20

what are weaknesses of stratified sampling?

Answer 20

time consuming (expensive)
complicated
inaccuracy (maths)