Research Methods- Sampling

Question 1

Target population:

Answer 1

Every member of the group that the investigator plans to study. As the target population could contain millions of people they can not all be studied.

Question 2

Target population

Researchers conduct their experiments on…

Answer 2

Researchers conduct their experiments on a smaller sample of participants, taken from the larger target population. The results/behaviour of that sample are assumed to apply to all the members of the target population, this is generalisation.

Question 3

Target population
Generalisability

Answer 3

Whether the results can be generalised or not depends on how representative the sample is of the target population, meaning the sample used in the study shares characteristics with the members of the target population. (e.g. gender, ethnicity, age, education level, income level)

Question 4

Random sampling:

Answer 4

Each member of the target population has a mathematically equal
chance of being in the experiment’s sample.

Question 5

How to conduct random sampling

Answer 5

1) The researcher needs a full list of the entire target population.
2) All names are entered into a container (or computer database)
3) A number of names equal to the sample required are pulled from the container
(the computer is instructed to randomly select the names).
4) The names selected from the sample.

Question 6

Evaluation
Random sampling
✅

Answer 6

• A random sample avoids researcher bias as the researcher cannot choose the participants they want to form the sample, avoiding the possibility the researcher picks participants they feel are likely to give a preferred result.

Question 7

Evaluation
Random sampling
❌

Answer 7

• Not every possible characteristic can be included in a stratified sample, and as the researcher decides which strata are important, this may result in bias.

• Time-consuming to establish strata and then randomly select from each stratum

Question 8

Systematic sampling:

Answer 8

Participants are chosen from a list of the target population.

Every Nth participant is chosen to form the sample (e.g. every 5th, or 10th or 100th name on the list)

Question 9

How to conduct Systematic sampling

Answer 9

1) The researcher needs a full list of the entire target population.

2)The researcher reads down the list selecting every Nth participant to form the sample (this can be any number for example every 5th, or 10th or 100th name)

3) The process continues until the sample required is chosen.

Question 10

Systematic sampling
Evaluation
✅

Answer 10

-Avoids researcher bias as the researcher cannot choose the participants they want in their sample.

-If there is an existing list of the target population (e.g. student registers of a school/college ) it can be a quick method of selecting a sample.

Question 11

Systematic sampling
Evaluation
❌

Answer 11

-By chance this method could result in an unrepresentative sample. E.g. too few members of one gender or with no members of a minority group.

-If the target population is very
ng a full list could be difficult.

Question 12

Opportunity sampling:

Answer 12

The researcher directly asks available members of the target population to take part in the research. This is likely to be individuals the researcher has easy access to and is familiar with.

Question 13

How to conduct opportunity sampling

Answer 13

1) Researcher directly asks any members from within the target population (that they have access to) to take part in the research.

2) Any individuals who agree to take part are added to the sample until the number of participants required is met.

Question 14

Opportunity sampling
Evaluation
✅

Answer 14

• This is the fastest way to get a sample for psychological research, reducing the time it takes to conduct research and likely reducing the cost involved compared to more complex sampling methods.

Question 15

Opportunity sampling
Evaluation
❌

Answer 15

• As the researcher decides who to ask, and importantly who to not ask to take part in their study, this could result in researcher bias, meaning the researcher may select participants they feel are likely to produce a preferred result.

• Opportunity samples are unlikely to be representative, as the participants chosen are the type of people the researcher has easy access to. For research conducted in universities, this is likely to be young undergraduate students.

Question 16

Volunteer sampling

Answer 16

Also known as a self-selecting sample, participants offer to take part after finding out about the research (they are not directly asked by the researcher). This is likely after seeing an advert in a newspaper or online.

Question 17

How to conduct volunteer sampling

Answer 17

How to conduct
1) Advertisements are placed where they are likely to be seen by members of the target population. (e.g. the gym for fitness enthusiasts, the pub for alcoholics)

2) The advert will include contact details and the researcher will enrol the volunteer into the sample when they are contacted by the volunteer.

Question 18

Volunteer sampling
Evaluation
✅

Answer 18

• Advertising for participants can reach a very large number of potential participants, especially if the newspaper or website is widely read.

• An easy sample to collect as participants are putting themselves forward rather than having to be found individually and contacted directly.

Question 19

Volunteer sampling
Evaluation
❌

Answer 19

• The sample may not be generalisable to the target population because of volunteer bias, the types of people who volunteer to take part are likely to have different characteristics to the target population, they are likely to be friendlier and have more free time available.

Question 20

Stratified sampling:

Answer 20

By selecting from within strata, The characteristics of participants within the sample are in the same proportion as found within the target population.

Question 21

How to conduct stratified sampling

Answer 21

1) Strata/ subgroups are identified along with their proportion in the target population (e.g. gender, ethnicity, education level).

2) Random sampling is then used to select the number of participants required from within each stratum. (e.g. 10% graduates and 90% non-graduates in the target population would result in 1 graduate and 9 non-graduates in a sample of 10)

Question 22

Stratified sampling
Evaluation
✅

Answer 22

• The sample is representative of the larger target population, meaning the results found with the sample should be generalisable to the target population.

-As the participants are randomly chosen from within each stratum this avoids researcher bias.

Question 23

Stratified sampling
Evaluation
❌

Answer 23

• Not every possible characteristic can be included in a stratified sample, and as the researcher decides which strata are important, this may result in bias.

• Time-consuming to establish strata and then randomly select from each stratum

Question 24

The ultimate implications of bias and a lack of generalisation are

Answer 24

the findings of a study are not a true reflection of human behaviour. If the findings are a result of bias, then the researcher is really measuring their (researcher bias) influence on the study not the manipulation of the IV.

Question 25

If the results lack generalisation…

Answer 25

then they may apply to a small subset of people but not the wider target population (often claimed to be all humans)

Question 26

Most participants are

Answer 26

WEIRD

Western: Born in the USA, UK or western Europe.

Educated: Experience an extended period of formal education.

Industrialised: Live in highly developed environments (e.g. cites)

Rich: Income levels far higher than the world average.

Democratic: Choose leaders collectively via voting.

Question 27

WEIRD Participants supporting study

Answer 27

Henrich et al (2010) found 96% of subjects in psychology studies were WEIRD participants, despite this only representing 12% of the world population. This raises serious questions about the generalisability of much of psychological research.