21. RM Sampling

Question 1

Define population.

Answer 1

This refers to a large group of individuals who the researcher may be interested in studying. For example students or adults with tourette’s.

Question 2

Define target population.

Answer 2

This is a sub-group of the general population.

Question 3

Define sample.

Answer 3

These are a group of people who take part in the research. These are drawn from the target population and is presumed to be representative of the population.

Question 4

What happens if the sample doesn’t reflect the characteristics of the target population?

Answer 4

Reduces generalisability so findings may not be useful.

Question 5

Define representative.

Answer 5

Is a group of participants selected from a larger population that closely matches the characteristics of the population as a whole so the sample is a fairly accurate reflection of the population from which the sample is drawn.

Question 6

Define generalisation.

Answer 6

The extent to which the findings and conclusions from a study can be broadly applied to the population- so if the sample is representative the more likely we can achieve this.

Question 7

Define bias.

Answer 7

When certain groups may be over/represented within the sample, eg too many women/men this limits the extent to which generalisation can be made to the population.

Question 8

Describe a random sample.

Answer 8

A sample of participants produced using a random technique such that every member of the target population has an equal chance of being selected.

Question 9

What is an example of a random sample?

Answer 9

Give all participants a number and use a random number generator to select your sample (pseudorandom technique).

Question 10

What is a strength of random sampling?

Answer 10

-Unbiased, all members of target population have an equal chance of selection.

Question 11

What is a weakness of random sampling?

Answer 11

-Time consuming and more effort because you need to obtain a list of all the members of your target population, then identify the sample and then contact the people identified and ask if they will take part.
-Random samples are often not random because not all the participants identified can be accessed to agree to take part. Therefore sample may be like a volunteer sample.

Question 12

Define a stratified sample.

Answer 12

Participants are selected from different subgroup’s frequency in that population.

Question 13

What is an example of a stratified sample?

Answer 13

Sub groups such as age groups, are identified and the number in each subgroup in the target population is identified. This is represented as a percentage (%) of the whole population.

Eg if 20% of target population is 11-16 years old. Then 20% of participants in the study should be in that age group. The researcher uses random selection to identify right number of 11-16 year olds.

Question 14

What is a strength of stratified sampling?

Answer 14

-Most representative as all subgroups are represented in proportion to the numbers in the target population.
-Specific subgroups can be chosen according to the variables considered to be important by the researcher. This increases control over possible extraneous variables.

Question 15

What is a weakness of stratified sampling?

Answer 15

-Decision about which subgroups to use may be biased, reducing the representativeness of the sample.
-This method involves a very lengthy process and those participants selected may not always agree to take part. This means that it is not a technique that is used much in psychological research. It is used when conducting opinion polls.

Question 16

Define a volunteer sample.

Answer 16

A sample of participants produced by asking for people willing to take part.

Question 17

What is an example of volunteer sampling?

Answer 17

Advertising in a newspaper or on a noticeboard.

Question 18

What is a strength of volunteer sampling?

Answer 18

-A convenient way to find willing participants. Researchers need committed participants for time-consuming studies and participants are less likely to drop out as they volunteered.
-May be a good way to get a specialised group of participants. This is called purposive sampling. For example, if you wanted to study the behaviour of medical students it would make sense to put an advert on the noticeboard of a medical school rather than standing around in a shopping centre hoping to find some medical students.

Question 19

What is a weakness of volunteer sampling?

Answer 19

-Sample is biased because volunteer participants are likely to be more highly motivated and/or with extra time on their hands than the population in general (volunteer bias).
-Volunteers may also be more willing to be helpful and thus may be more prone to guessing the aims of the study and responding to demand characteristics (researcher effects).
-

Question 20

Define an opportunity sample.

Answer 20

A sample of participants produced by selecting people who are most easily available at the time study.

Question 21

What is an example of opportunity sampling?

Answer 21

Asking people in the common room at school and selecting those who are available to take part in the research.

Question 22

What is a strength of opportunity sampling?

Answer 22

-The most convenient technique because it takes little preparation. You just use the first participants you can find. This means it takes less time to locate your sample than if using one of the other techniques.
-It may be the only technique available because the whole target population cannot be listed (needed for random and stratified sampling).

Question 23

What is a weakness of opportunity sampling?

Answer 23

-Inevitably biased because the sample is drawn from a small part of the target population and therefore is not likely to be representative. For example, shoppers in a city centre on a Monday morning from a small part of the population, eg they are largely not people at work

Question 24

Define a systematic sample.

Answer 24

Every nth member of the target population is selected and a sampling frame is produced.

Question 25

What is an example of systematic sampling?

Answer 25

To print out all of the school registers and select every 5th name until you have selected 50 students.

Question 26

What is a strength of systematic sampling?

Answer 26

Avoids researcher bias, as once the system has been established the researcher has no influence over who is chosen.

Question 27

What is a weakness of systematic sampling?

Answer 27

Can be difficult to achieve and time-consuming.

Question 28

Define an aim.

Answer 28

-The aim is a statement of a study’s purpose.
-When carrying out a piece of research, it is essential that you have an aim in mind.
-It is what the researcher is trying to find out.
-The aim is broader and less precise than a hypothesis.

(Milgram 1963- investigated how far people would go in obeying an instruction to harm another person).

Question 29

Define a hypothesis.

Answer 29

A hypothesis can be defined as a precisely worded testable statement, made at the outset of an investigation, which indicates the expected outcome of a study.

Question 30

What are the 2 key types of hypothesis?

Answer 30

The hypothesis either states a predicted difference between an independent and dependent variable (an experimental hypothesis), or it states a predicted relationship between variables (in the case of a correlational analysis).

Question 31

Define an alternative (experimental) hypothesis.

Answer 31

-States that the expected effect of the manipulated variable on the outcome is statistically significant.
-May be a directional or a non-directional hypothesis.

Question 32

Define a directional (one tailed) hypothesis.

Answer 32

-A directional hypothesis states the direction of the predicted difference.
-A one tailed directional hypothesis predicts the nature of the effect of the independent variable on the dependent variable.

-Eg teenagers will sleep for significantly more hours in a week than adults aged 20-40

Question 33

Define a non-directional (two tailed) hypothesis.

Answer 33

-A non directional hypothesis predicts a difference between two conditions but does not specify in which direction the difference will be.
-A two tailed non directional hypothesis predicts that the independent variable will have an effect on the dependent variable, but the direction of the effect is not specified.

-Eg there will be a significant difference between teenagers and adults aged 20-40 in the numbers of hours they sleep in a week.

Question 34

Define the null hypothesis.

Answer 34

States that is no effect in the study (no significant difference).

Question 35

Describe operationalisation.

Answer 35

-The hypothesis should be operationalised (the variables and how they will be measured must be clear in the hypothesis).
-Eg “After drinking 300ml of Fanta, participants will say more words in the next 5 minutes than participants who drink water”.