# 2.3.1 Participants & Probability sampling Flashcards

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1
Q

what is a target population?

A

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

2
Q

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

A

children aged 5 - 11

3
Q

in an ideal world who would you study?

A

4
Q

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

A

target population is often too large

5
Q

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

A

a small representative sample

6
Q

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

A

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

7
Q

when deciding sample size what do you need to consider?

A

time
money
resources

8
Q

what is sampling?

A

how participants are selected for research studies

9
Q

what is probability sampling?

A

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

10
Q

what is a sampling frame?

A

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

11
Q

give examples of sampling frames:

A
```registers - school, work, births, marriages
medical records
phonebooks
gym membership
DVLA list```
12
Q

what is random sampling?

A

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

13
Q

what is a strength of random sampling?

A

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

14
Q

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

A

accidental bias - e.g. all boys selected

15
Q

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

A
1. cant get a list of everyone in target population
2. cant contact everyone randomly selected
3. those selected may refuse to participate
16
Q

what is systematic random sampling?

A

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

17
Q

what is stratified sampling?

A

target population divided into sub categories

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

18
Q

(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?

A

2.5%

19
Q

what is the most representative probability sampling method?

A

stratified sampling

20
Q

what are weaknesses of stratified sampling?

A

time consuming (expensive)
complicated
inaccuracy (maths)