PART 1: Sampling How we select our sample will directly influence the external v
ID: 3043513 • Letter: P
Question
PART 1:
Sampling
How we select our sample will directly influence the external validity of the study. If a sample isrepresentative, then our external validity is stronger. If a sample is non-representative, then our external validity is weaker.
QUESTIONS:
1.
You are interested in looking at the relationship between student-to-teacher ratio and GPA at California 2- and 4-year colleges. You suspect that average GPA is higher at 2-year colleges where student-to-teacher ratio is low, relative to 4-year colleges colleges that have higher student-to-teacher ratios.
You would like to draw a representative sample, but in previous attempts you ended up with a sample that was entirely from 2-year colleges. You realize that there are far more students at 2-year colleges (1.7 million in 2010) than at 4-year colleges (650,000 in 2010). That means that roughly 72% of the enrolled students were enrolled in 2-year colleges and roughly 28% were enrolled in 4-year colleges.
To select your sample of 1000 students, you compile a list of the names of all the students at 2-year colleges, print each name on a slip of paper and put all the paper slips in a hat. You draw out 720 names. You then compile a list of the names of all the students at 4-year colleges, print each name on a slip of paper and put all the paper slips in a hat. You draw out 280 names.
What sort of sampling technique are you using now? SELECT ONE OF THE FOLLOW:
A. cluster sampling
B. multistage sampling
C. convenience sampling
D. simple random sampling
E. stratified random sampling
F. quota sampling
2.
You are interested in looking at the relationship between student-to-teacher ratio and GPA at California 2- and 4-year colleges. You suspect that average GPA is higher at 2-year colleges where student-to-teacher ratio is low, relative to 4-year colleges colleges that have higher student-to-teacher ratios.
You know that there are far more students at 2-year colleges (1.7 million in 2010) than at 4-year colleges (650,000 in 2010) in California. That means that roughly 72% of the enrolled students were enrolled in 2-year colleges and roughly 28% were enrolled in 4-year colleges.
You really want to accurately gauge the average GPA at each type of college. You want to ensure that you have the same number of participants from each type of college. To select your sample of 1000 students, you compile a list of the names of all the students at 2-year colleges, print each name on a slip of paper and put all the paper slips in a hat. You draw out 500 names. You then compile a list of the names of all the students at 4-year colleges, print each name on a slip of paper and put all the paper slips in a hat. You draw out 500 names.
What sort of sampling technique are you using now? SELECT ONE OF THE FOLLOW:
A. cluster sampling
B. multistage sampling
C. convenience sampling
D. simple random sampling
E. stratified random sampling
F. quota sampling
3.
You are interested in looking at the relationship between student-to-teacher ratio and GPA at California 2- and 4-year colleges. You suspect that average GPA is higher at 2-year colleges where student-to-teacher ratio is low, relative to 4-year colleges colleges that have higher student-to-teacher ratios.
You work with your campus chapter of the National Honor Society in Psychology (PsiChi) to obtain a list of all their members at the other 2- and 4-year colleges in California. You email out to all those members and ask them to interview 5 students on their campus. You suggest that they don't just interview their friends, but ask people walking around campus. Each of your new research assistants reports back the type of college (2- or 4-year) and the GPA of the 5 participants they recruited. You are very pleased that thousands of students gathered data.
What sort of sampling technique have you used? SELECT ONE OF THE FOLLOW:
A. cluster sampling
B. multistage sampling
C. convenience sampling
D. simple random sampling
E. stratified random sampling
F. quota sampling
Explanation / Answer
1. F. Quota Sampling.
It is a sample including a pre determined % of each sub category of the target population.
2.E. Stratified Ramndom Sampling
Because it takes a sample of equal proportion from each strata of the population.Here the strata are the 2-year and the 4-year colleges.
3.C. Convenience Sampling
Because each member asks people walkingin the campus based on their convenience.
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