Practice 3 | Answers posted Tuesday, December 9th |
- Pg 714: 13.15a by hand OR SAS. Also state the null
and alternate hypothesis in terms of the parameters and
the problem, and check the assumptions.
- Pg. 732: 13.35 b-d by hand and by SAS. Is the sample
size large enough? Is this a test of homogeneity or
of independence? Why?
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Practice 2 | Answers
posted Saturday, November 22nd |
- Page 522: 11.13c, also calculate the SSE and the MSE.
- Page 526: 11.19 using SAS. Also, check that the assumptions for
performing regression are met, conduct a test of the null hypothesis
that beta_1=0, and verify that the degrees of freedom in the ANOVA
table are correct.
- Page 548: 11.55b. That is, describe the relationship between exposure time
and goodness of view.
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9 | Due: Wednesday, November 19th
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- Page 459: 10.18 a,b,c
- Page 461: 10.25 b-d. Generate your own SAS output. and
check the assumptions.
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8 | Due: Wednesday, November 12th
| - Page 393: 9.13 Construct the confidence interval in part a by
hand, assuming the variances are equal.
Use SAS to calculate the means and variances for part a and to do part b.
- also, c) By hand AND using SAS, conduct a test of the hypothesis that
the two groups have
the same mean against the alternate hypothesis that the group means
are different using alpha=0.05 and the result you found in part b concerning
the variances.
- Page 416: 9.51
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7 | Due: Monday, October 27th
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- Pg. 339: 8.27a (note the mean and SD are given on
pg. 340). Also test H0: sigma2=1 vs. HA: sigma2>1 by hand. Finally,
describe how you would check if the assumptions for these tests are met, and
how closely they need to hold for each one.
- Pg. 357: 8.62
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6 | Due: Wednesday, October 22nd
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- Consider the "Scallops, Sampling, and the Law" box write-up and focus
questions on page 319. The rule of comparing x-bar to a cut-off could
be considered unfair because we don't really want to compare x-bar to the
cut-off... we want to compare mu to the cut-off. In this case, what we
want is for mu to be at least one for the catch to be legal.
- By hand, construct a 95% confidence interval for the mean weight
measurement for a bag of shrimp from this boat. (You may use the
facts that x-bar=0.9317 and s=0.0753).
- Does the catch appear to be legal?
- By hand, construct a 95% confidence interval for the standard deviation
for the weight measurements for a bag of shrimp from this boat. (Again,
you may use the fact that x-bar=0.9317 and s=0.0753).
- Use SAS to construct both a 95% CI for the mean and a 95% CI for
the standard deviation of the weights of the bags. Remember that whenever
you use SAS with your homework you need to include a copy of the code from
the Program Editor window and the appropriate part of the output.
(The CI for the sd may be slightly different in SAS than by hand.)
- Use SAS to construct a Q-Q plot of the observed weights.
Does the data seem like it came from a distribution that was very close to
normal, somewhat close to normal, or not at all normal?
- Based on your answer to e, do you trust the confidence interval you made
for the mean to actually be a 95% confidence interval for the mean? do you
trust the confidence interval you made for the standard deviation to actually
be a 95% confidence interval for the standard deviation?
- Pg. 313: 7.38 a,b (Use the Agresti and Coull correction and show your work!)
- Pg. 320: 7.54 (Show your work! This one is a lot easier if you've read
page 318 and 319)
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5 | Due: Wednesday, October 15th
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- Pg. 272: 6.8 and also
f) Would s2 be unbiased for sigma2 if
we divided by n instead of n-1?
- For n=14 (df=13), find P(t<3.012),
P(chi2>22.3621),
and t0 such that
P(-t0 < t < t0)=0.95
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4 | Due: Monday, October 6th
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- Pg. 234: 5.16a,c; 5.20c; 5.24d
- Pg. 248: 5.57c Show your work and that n is large enough
- Pg. 280: 6.28a-b Also say why the np, n(1-p) rule does not apply.
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Practice |
Answers
posted Monday, September 22nd |
- Pg. 170: 3.124a
- Pg. 186: 4.22a
- Pg. 201: 4.52, also
f) What is the probability that the psychic would get exactly
two correct if they had no ESP?
g) What is the probability that the psychic would get exactly two correct
if they had ESP with p=0.5?
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3 | Due: Wednesday, September 17th
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- Page 60: 2.61, show your work
- Page 68: 2.75, explain how you got your answers
- Page 117: 3.6
- Page 147: 3.62, also
c) What is P(A intersect B), P(A|B), and P(A U B)
if A and B are mutually exclusive.
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2 | Due: Wednesday, September 10th
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For this assignment use the data set in problem 2.100 on page 84.
(A copy of the data set is on the disk that came with your text book.
Remember to include a copy of the code you ran, and any output you refer
to with your answers.)
- Using SAS calculate the mean, median, and standard deviation
of this data set.
- In general, would the mean or median be more useful for getting
an idea of how much a new graduate would be paid in a given field? Why?
- Would you classify any of the reported salaries as outliers?
Why or why not?
- Use SAS to construct a Q-Q plot for this data. Does the data
appear to follow a normal curve for the most part?
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1 | Due: Wednesday, September 3rd
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- Page 17: 1.26 also justify your answer to part d
- Page 53: 2.48 b-c
also construct a historgram for this data
is it skewed? which direction?
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