Selecting and Using Participants

Question 1

What is random sampling?

Answer 1

1. When every member of the target group has an equal chance of being selected for the sample,
2. Could be done manually or by using a computer.

Question 2

Advantages of random sampling?

Answer 2

1. Random sampling is ‘fair’ - everyone has an equal chance of being selected and the sample is likely to be representative.

Question 3

Limitations of random sampling?

Answer 3

1. Method doesn’t guarantee a representative sample - there is still a chance that some subgroups in the target group may not be selected,
2. Also, if the target group is large it may not be practical to give everyone a number that might be picked, so in practice completely random samples are rarely used.

Question 4

What is opportunity sampling?

Answer 4

1. When the researcher samples whoever is available and willing to be studied,
2. Many researchers work in universities, they often use opportunity samples made up of students.

Question 5

Advantages of opportunity sampling?

Answer 5

1. This is a quick and practical way of getting a sample.

Question 6

Limitations of opportunity sampling?

Answer 6

1. Sample is unlikely to be representative of the target group or population as a whole,
2. Means that we can’t confidently generalise the findings of the research,
3. However, because it is quick and easy, opportunity sampling is often used.

Question 7

What is volunteer sampling?

Answer 7

1. When people actively volunteer to be in a study by responding to a request for participants advertised by the researcher, e.g. in a newspaper or on a newsboard,
2. Researcher may select only those who are suitable ofr the study.

Question 8

Advantages of volunteer sampling?

Answer 8

1. If an advert is placed porminently, a large number of people may respond, giving more participants to study,
2. This may allow more in-depth analysis and more accurate statistical results.

Question 9

Limitations of volunteer sampling?

Answer 9

1. Even though a large number of people may respond, these will only include people who saw or heard about the advertisement - no one else would have a chance of being selected,
2. Also, people who volunteer may be more cooperative than others, so the sample is unlikely to be representative of the target population.

Question 10

What is systematic sampling?

Answer 10

1. Where every nth name from a sampling frame (a record of all the names in a population) is taken, e.g. every 3rd name from a register,
2. This is useful if there is a sampling frame available.

Question 11

Advantages of systematic sampling?

Answer 11

1. This is a simple and effective way of generating a sample with a random element,
2. It also means that the population is more likely to be evenly sampled than by using opportunity or volunteer samples.

Question 12

Limitations of systematic sampling?

Answer 12

1. Subgroups might be missed,
2. It will not be representative if the pattern used for the samples coincides with a pattern in the population.

Question 13

What is stratified sampling?

Answer 13

1. Where all of the important subgroups in the population (e.g. different age or ethnic groups) are identified and a proportionate number of each is randomly obtained,
2. In example, in a class of 20 students, ten are 16 years old, eight are 17, and two are 18. If you take a stratified sample of 10 students, the number of 16, 17, and 18-year-olds in the sample need to be 50% of the full class.

Question 14

Advantages of stratified sampling?

Answer 14

1. Can produce fairly representative samples. Can also be used with random and systematic sampling.

Question 15

Limitations of stratified sampling?

Answer 15

1. Can take a lot of time and money to do it, and some subgroups may be missed,
2. Can often be difficult to identify traits and characteristics effectively enough to stratify the sample property.

Question 16

What is the Hawthorne Effect?

Answer 16

1. If people are interested in something and in the attention they are getting, then they show a more positive response, try harder at tasks, and so on,
2. This means that their results for tests are often artificially high which could make the researcher’s conclusions invalid,
3. The opposite can occur when participants are uninterested in the task.

Question 17

What are demand characteristics?

Answer 17

1. There are aspects of studies that allow the participants to form an idea of its purpose,
2. If they think they know what kind of response is expecting from them, they may show that response to ‘please’ the researcher,
3. Either way, the conclusions drawn from the study would be invalid.

Question 18

What is social desirability bias?

Answer 18

1. People usually try to show themselves in the best possible light,
2. So in a survey, they may not be completely truthful, but give answers that are more socially acceptable instead,
3. This would make the results less valid.

Question 19

What is researcher bias?

Answer 19

1. The researcher’s expectations can influence how they design their study and how they behave towards participants,
2. Their expectations may influence how they take measurements and anlayse their data, resulting in errors that can lead, for example, to accepting a hypothesis that was actually false,
3. Their expectations may also lead them to only ask questions about what they are interested in, and they may focus on the aspects of the participant’s answers which fit their expectations.

Question 20

What are investigator effects?

Answer 20

1. Can be anything that the researcher does which can affect how the participants behave,
2. If a researcher’s expectations influence how they behave towards their participants, the participants might respond to demand characteristics,
3. A researcher’s expectations could result in them asking leading questions. Finally, the participant may react to the behaviour or appearance of an investigator and answer differently.