Business Statistics
Quiz #5 Solutions
12/11/08
Name: ____________________________________
Instructions: You have 20 minutes to complete this quiz. For each question,
circle the answer that is most correct.
1. In hypothesis testing, the p-value is the probability of seeing data as extreme
or more extreme under the alternate hypothesis.
a) True
b) False
2. In the JMP output to the right for a two-sample t-test, the null hypothesis of
a = b is _____________.
a) accepted
b) rejected
3. In a paired t-test, a critical assumption is that the two variables are
independent.
a) True
b) False
4. In the expression, Y = bX + a, the slope is b.
a) True
b) False
5. The slope of a fitted line measures the change in Y for each unit change in X.
a) True
b) False
6. In regression, X is called the independent variable; it is the varaible that we
suspect has an influence on the value of the response.
a) True
b) False
7. The correlation coefficient (r) is a measure of the strength of the linear
relationship between two variables.
a) True
b) False
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Business Statistics
Quiz #5 Solutions
12/11/08
8. The correlation coefficient (r) must be between +1 and -1, inclusive.
a) True
b) False
9. Residuals are the prediction errors in the sample; that is, they are the
difference between an actual value ( y ) and its predicted value ( ŷ ).
a) True
b) False
10. In regression, R2 is called the ___________.
a)
b)
c)
d)
Coefficient of determination
Coefficient of regression variability
Regression coefficient
Coefficient of regression deviation
Review Questions
11. Which of the following is not a type of variation that we discussed in class:
a)
b)
c)
d)
e)
Longitudinal
Cross sectional
Time series
Random
All of the above are types of variation
12. Which of the following is not a measure of variation:
a)
b)
c)
d)
e)
Interquartile range
Sample standard deviation
Mode
Population variance
All the above are measures of variation
13. When describing a normal distribution, which one of (a) through (d) is not true:
a)
b)
c)
d)
e)
The distribution is unimodal.
The distribution is symmetric.
The mean equals the median.
The normal distribution has thin tails.
All of the above are true.
14. Which of the following statement or statements are true:
a) The terms standard error and sampling distribution mean the same thing.
b) The distribution of a sample statistic is called a sampling
distribution.
c) The sampling distribution and the t distribution are the same thing.
d) Both (a) and (b) are true.
e) None of the above are true.
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Business Statistics
Quiz #5 Solutions
12/11/08
15. Which of the following statements (a) through (c) are true:
a) Means are less variable than individual observations.
b) The standard error of the sample mean equals the standard deviation of
the observations divided by the square root of the number of observations.
c) The Central Limit Theorem says that averages have an approximately
normal distribution.
d) Only (a) and (b) are true.
e) All of the above are true.
16. Using a random sample is protection against (unknowingly) selecting what
kind of sample:
a)
b)
c)
d)
e)
Blemished
Notional
Biased
Negative
None of the above.
17. Which of the following sampling methods is not a type of random sample:
a)
b)
c)
d)
e)
Stratified
Cluster
SRS
Convenience
All of the above are types of random samples.
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