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HP 340 practice midterm – Fall 2009
The exam will be closed book, closed notes, with a table of (some) formulas, and
tables of critical values for the T and Z distributions like Table C.1 and C.2 in
Appendix C of your textbook. In this practice exam, several of the computation
exercises are pulled from the textbook; answers can be found in Appendix E.
These questions may not mirror those on the exam, but if you can manage these,
you should do fine on the actual midterm.
You will want to flip through the slides
for Chapter 9 before beginning this practice exam.
Conceptual questions:
1)
(Errors and intervals)
At least two types of testing error are possible.
a.
The significance level
α
represents a limit for what type of error?
b.
Why should experimenters ‘fail to reject the null’ in the absence of
statistically significant test results?
(Is this the same as accepting it?)
c.
A
(1–
α
) confidence interval for an estimate
varies with changes in
α
.
For example, an experimenter testing at an
α
level of 0.01 might be
inclined to report their estimates in terms of a 99% confidence interval.
How would their (1
α
) intervals change if
α
were increased to 0.05?
d.
Which type of error occurs if a true alternative hypothesis is rejected?
2)
(Types of variables) Occasionally, an investigator will (temporarily) replace
missing observations with an appropriate estimate of their expected value,
often to complete exploratory analyses.
A measure of central tendency – the
mean, median, or mode of a variable – is often used for this purpose, but the
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This note was uploaded on 11/30/2009 for the course HP 400m at USC.
 '07
 Nezami,Borovay

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