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Q
uantitative
R
easoning &
P
roblem
S
olving
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© 2014 Pacific Crest
5. What is the difference between inventorying and sampling? When would you choose to do one
versus the other?
6. What are the issues in the sampling problem that would encourage stratification?
A
Successful Performance
Successful application of your learning looks like this
As you begin to apply what you’ve learned, you should have a good idea of what success looks like.
A SUCCESSFUL
PERFORMANCE
I evaluate the quality and effectiveness of a sampling design. I...
●
Investigate the purpose and details of the sampling strategy used
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Determine the appropriateness of a sampling strategy chosen
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Identify the relationship between margin of error, cost, and sample size
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Document all concerns and issues that occur when implementing the sampling design
D
emonstrate Your Understanding
Apply it and show you know in context!
1. When the sample statistic being measured is the sample mean, the standard error
x
σ
is calculated as:
x
n
σ
σ
=
where σ is the standard deviation of the population distribution and n is the sample size.
If a surveyor wanted to achieve half the measurement error (cut the standard error in half), by how
much does the sample size need to increase?
2. You are interested in determining whether the mean GPA of students over 21 is different from the
mean GPA of students under 21. Which sampling method would you recommend for the situation
above? Why? What potential biases might you encounter when using this sampling method?
3. Identify a life situation where the inference made about a population parameter from a sample
statistic was significantly wrong. Describe what caused the problem.