7.2: Sampling Flashcards
A head teacher wanted to increase recycling in his school. He arranged for the canteen to have three bins, one for cardboard, one for plastic and one for food waste. A month later, a psychology teacher decided to see if the students were recycling. One lunch break she watched different students going to the bins. Each time, she wrote down which of the three types of waste they recycled. She positioned herself so that the students could not see her but so that she had a clear view of the bins.
Explain the sampling technique the teacher used to record her observations (2 marks)
Event sampling - The teacher recorded each time one of the three types of item was recycled
A team of researchers used a stress scale to measure the amount of stress that individual workers at a factory experienced and the number of days they were off sick over a 6 month period. The researchers found that as the amount of stress increased, the number of days absent also increased.
Explain how the researchers might have gained a systematic sample for this study (1 mark)
A systematic sample would be gained by selecting every nth person from a population
A psychologist wanted to see if verbal fluency is affected by whether people think they are presenting information to a small group of people or to a large group of people.
The psychologist needed a stratified sample of 20 people. She obtained the sample from a company employing 60 men and 40 women.
The participants were told that they would be placed in a booth where they would read out an article about the life of a famous author to an audience. Participants were also told that the audience would not be present, but would only be able to hear them and would not be able to interact with them.
There were two conditions in the study, Condition A and Condition B.
Condition A: 10 participants were told the audience consisted of 5 listeners.
Condition B: the other 10 participants were told the audience consisted of 100 listeners.
Each participant completed the study individually. The psychologist recorded each presentation and then counted the number of verbal errors made by each participant.
Explain one advantage of using a stratified sample of participants in this study (2 marks)
One advantage of using a stratified sample of participants in this study is that it ensures that the sample is truly representative
A psychologist wanted to see if verbal fluency is affected by whether people think they are presenting information to a small group of people or to a large group of people.
The psychologist needed a stratified sample of 20 people. She obtained the sample from a company employing 60 men and 40 women.
The participants were told that they would be placed in a booth where they would read out an article about the life of a famous author to an audience. Participants were also told that the audience would not be present, but would only be able to hear them and would not be able to interact with them.
There were two conditions in the study, Condition A and Condition B.
Condition A: 10 participants were told the audience consisted of 5 listeners.
Condition B: the other 10 participants were told the audience consisted of 100 listeners.
Each participant completed the study individually. The psychologist recorded each presentation and then counted the number of verbal errors made by each participant.
Explain one advantage of using a stratified sample of participants in this study (2 marks).
One advantage of using a stratified sample of participants in this study is that it ensures that the sample is truly representative, why?
One advantage of using a stratified sample of participants in this study is that it ensures that the sample is truly representative, because different types of people (males/females) working in this company are represented in the sample in the correct proportion
A psychologist wanted to see if verbal fluency is affected by whether people think they are presenting information to a small group of people or to a large group of people.
The psychologist needed a stratified sample of 20 people. She obtained the sample from a company employing 60 men and 40 women.
The participants were told that they would be placed in a booth where they would read out an article about the life of a famous author to an audience. Participants were also told that the audience would not be present, but would only be able to hear them and would not be able to interact with them.
There were two conditions in the study, Condition A and Condition B.
Condition A: 10 participants were told the audience consisted of 5 listeners.
Condition B: the other 10 participants were told the audience consisted of 100 listeners.
Each participant completed the study individually. The psychologist recorded each presentation and then counted the number of verbal errors made by each participant.
Explain how the psychologist would have obtained the male participants for her stratified sample.
Show your calculations (3 marks)
The psychologist would have obtained the male participants for her stratified sample by the manual method - To put all 60 male names in a hat (or similar) and determine the proportion of males needed to mirror the number of males in the target population, which is 60%
A psychologist wanted to see if verbal fluency is affected by whether people think they are presenting information to a small group of people or to a large group of people.
The psychologist needed a stratified sample of 20 people. She obtained the sample from a company employing 60 men and 40 women.
The participants were told that they would be placed in a booth where they would read out an article about the life of a famous author to an audience. Participants were also told that the audience would not be present, but would only be able to hear them and would not be able to interact with them.
There were two conditions in the study, Condition A and Condition B.
Condition A: 10 participants were told the audience consisted of 5 listeners.
Condition B: the other 10 participants were told the audience consisted of 100 listeners.
Each participant completed the study individually. The psychologist recorded each presentation and then counted the number of verbal errors made by each participant.
Explain how the psychologist would have obtained the male participants for her stratified sample.
Show your calculations (3 marks).
The psychologist would have obtained the male participants for her stratified sample by the manual method - To put all 60 male names in a hat (or similar) and determine the proportion of males needed to mirror the number of males in the target population, which is 60%.
What would they then do?
They would then calculate 60% of 20 = 12 and draw out 12 names
Students often claim that listening to music helps them to concentrate. A psychologist was not aware of any previous research in this area. She decided to investigate this claim.
Forty students from a nearby sixth form centre volunteered to take part in her study. They each answered the following question:
‘Do you think that you concentrate on your work ‘better’, ‘worse’ or ‘the same’ if you listen to music while working?’
She obtained the results in Table 1.
Table 1:
Responses to question - ‘Do you think that you concentrate on your work ‘better’, ‘worse’ or ‘the same’ if you listen to music while working?’
Better = 22
Worse = 8
The same = 10.
Explain why using stratified sampling might improve this study (2 marks)
Using stratified sampling might improve this study, because stratified sampling increases representation by sampling many subsets of students, which therefore increases generalisability
Students often claim that listening to music helps them to concentrate. A psychologist was not aware of any previous research in this area. She decided to investigate this claim.
Forty students from a nearby sixth form centre volunteered to take part in her study. They each answered the following question:
‘Do you think that you concentrate on your work ‘better’, ‘worse’ or ‘the same’ if you listen to music while working?’
She obtained the results in Table 1.
Table 1:
Responses to question - ‘Do you think that you concentrate on your work ‘better’, ‘worse’ or ‘the same’ if you listen to music while working?’
Better = 22
Worse = 8
The same = 10.
Explain why using stratified sampling might improve this study (2 marks).
Using stratified sampling might improve this study, because stratified sampling increases representation by sampling many subsets of students, which therefore increases generalisability.
In addition, what?
In addition, stratified sampling reduces research bias, because the subsets of students are selected randomly
