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M 2/2/15
D
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HW due (both blocks):
1. Read pp. 525-534.
2. Write #10.1, 10.2acde, 10.3, 10.4, and 10.5 on pp. 529-530.
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T 2/3/15
E
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HW due:
1. Write #10.12, 10.13, 10.17, and 10.18 on pp. 534-536.
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W 2/4/15
F
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No class.
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Th
2/5/15
G
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HW
due (both blocks):
1. Earlier in the year, we discussed the calculation of PPV (positive
predictive value) by using a tree diagram. We learned how to calculate the
likely number of true positives, false positives, true negatives, and false
negatives in a situation involving screening for an asymptomatic disease. If
the disease has incidence probability i, and if the sensitivity and specificity of the test are,
respectively,
p
= P(+ reading | diseased) and r = P(– reading | ~diseased),
then 
Here, NPV refers to the negative
predictive value, i.e., P(~diseased
| – reading).
(a) Construct a tree diagram, and use it to derive the formulas for PPV and
NPV given above.
(b) Compute the expected number of diseased individuals in a random sample of
size n. Explain briefly (one
sentence) why your answer is correct, using the terminology of our course.
(c) Compute the probability of a Type I error relative to the entire
population of test subjects. This is moderately difficult but is well within
your current capability. Note: This
is not what we usually mean when we
ask for the probability of Type I error.
(d) Compute the probability of Type I error given that the test subject is
truly diseased.
(d´) Compute the probability of Type I error, using the usual definition
(i.e., the conditional probability that H0
is rejected, given that H0
is true).
(e) Compute the probability of a Type II error relative to the entire
population of test subjects. Note:
This is not what we usually mean
when we ask for the probability of Type II error.
(f) Compute the probability of Type II error given that the test subject is
truly free of disease.
(f´) Compute the probability of Type II error, using the usual definition
(i.e., the conditional probability that H0
is not rejected, given that H0
is false).
2. For each of the following scenarios, explain what a Type I error would
mean (in terms of real-world consequences)
and what a Type II error would mean (again, in terms of real-world consequences). Also state the “bottom
line”: in other words, which type of error would be more serious, in your
opinion. The first one is done for you as an example.
(a) H0: The true number
of missiles being fired at the U.S. equals 0.
Ha:
The true number of missiles being fired at the U.S. is greater than 0.
Type I error: The U.S. launches a counterstrike in response to a false alarm.
The world is destroyed.
Type II error: The U.S. fails to detect an incoming missile attack in time to
launch a full counterstrike. However, submarine-launched missiles survive and
are sent back at the attacking country. The world is destroyed.
Bottom line: No difference.
(b) H0: The true
blood-alcohol content of a certain 21-year-old driver at a checkpoint is
0.079%, just below the legal limit.
Ha:
The true blood-alcohol content of a certain 21-year-old driver at a
checkpoint is greater than or equal to 0.080% (i.e., greater than 0.079%, if
readings are to the nearest 0.001%).
(c) H0: The true number
of cancerous cells in a certain biopsy specimen equals 0.
Ha:
The true number of cancerous cells in a certain biopsy specimen is greater
than 0.
(d) H0: The true mean number
of gallons dispensed in 10.000-gallon sales registered by a certain gasoline
pump is 10.000.
Ha:
The true mean number of gallons dispensed in 10.000-gallon sales registered
by a certain gasoline pump is not equal to 10.000.
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F 2/6/15
A
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HW due (both blocks):
1. Reread yesterday’s assignment. Note that the wording for #1(d) and (f) has
been clarified.
2. Make sure you have a complete set of correct answers for yesterday’s
assignment. All words should be legible. This assignment may be collected a
second time.
3. Answer #1(d´) and #1(f´) from yesterday’s assignment. If you wish, you may
fold those in amidst the work that you did for yesterday, or you may put them
on a fresh sheet of paper.
4. Read pp. 537-548. For the tan box in the middle of p. 545, we will
substitute this handout, which
you should also read.
5. Memorize the PHA(S)TPC steps (name only), and be prepared for a possible
quiz. For today’s quiz, all you need to know is the basics: Parameter(s), Hypotheses, Assumptions for identified
test, Sketch (optional) of
sampling distribution, Test
statistic, P-value, Conclusion
in context.
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M 2/9/15
B
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HW due (Block 3): Write
#10.23, 10.24, 10.25, and 10.30 on p. 548. Full PHA(S)TPC procedures are required
for #10.30.
In class: Review.
Block 4: No class.
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T 2/10/15
C
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Block 3: No class.
HW due (Block 4): Write #10.23, 10.24, 10.25, and 10.30 on p. 548. Full PHA(S)TPC procedures are required
for #10.30.
In class: Review.
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W 2/11/15
D
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Test (100 pts.) on all recent material,
through p. 548.
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Th
2/12/15
E
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Block 3: No additional
HW due. In class: We failed (yet again) to find any evidence that educated
guessing is superior to random guessing when answering multiple-choice
questions. Videos.
Block 4: No additional HW due. In class: Review of test, videos.
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F 2/13/15
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No school
(teacher professional day).
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F 2/16/15
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No school
(holiday).
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T 2/17/15
F
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No class.
(Also, no school because of snow.)
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W 2/18/15
G
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HW due (both
blocks):
Over the long weekend, cuddle up with your Barron’s AP review book. You
should have one, since it is a required text for the course. If you do not
have one, now is the time to buy a copy. Time spent with this book is like
money in the bank. A written time log is recommended but not required. Keep
all of the problems you worked on together in one place (either your 3-ring
binder or a spiral-bound notebook with a dedicated section for statistics
review). Be prepared to report on what
you did over the weekend with your review book.
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Th
2/19/15
A
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HW due (both
blocks):
Complete the entire 2/11/2015 test to
100%. For page 1, it is sufficient to write the answer to each question; no work
is necessary, and you may write your answers either on a printout of page 1
or on a sheet of standard HW paper (your choice). For pages 2 and 3, full
work is required. If you finished pages 2 and 3 in class yesterday, then
congratulations! You have a short assignment consisting of page 1 only.
Legibility is expected. USE PENCIL.
You may work with your pairs partner for all portions of this assignment.
Be prepared to turn in this assignment. It may be graded in full, or it may
be spot-checked for correctness. Unlike most homework assignments, where
effort and evidence of time spent are all that are required, this assignment
requires correct answers and correct work.
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F 2/20/15
B
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Block 3 HW due: Read pp. 550-570; write #10.65 and
#10.66 on p. 570.
Block 4: No class.
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M 2/23/15
C
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Block 3: No class. However, that doesn’t mean
you have no HW. Please work on your Barron’s review book for at least 10
minutes. Keep your written record in the same place that you used last week, and
be prepared to report on what you did. If you didn’t quite finish last
Friday’s assignment, you may use the time to finish up those problems. Note: If you have the school musical
or other extenuating reasons for being unable to do the 10 minutes of review
work this weekend, a brief note to that effect in your review notebook will
be acceptable.
Block 4 HW due:
1. Read pp. 550-570; write #10.65 and #10.66 on p. 570.
2. If time permits, please work on your Barron’s review book for at least 10
minutes. Keep your written record in the same place that you used last week,
and be prepared to report on what you did. Note: If you have the school musical or other extenuating reasons
for being unable to do the 10 minutes of review work this weekend, a brief note
to that effect in your review notebook will be acceptable. Assignment #1 is
still required, however.
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T 2/24/15
D
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HW due (both
blocks):
For this assignment, you may
interleave reading notes and written work if you wish (labeled as “#1-7 from
web page”), or you may separate them. If you separate them (for example, with
reading notes in a spiral notebook and written work on a 3-hole-punched
sheet), then you may label the written problems as “#3, 4 (10.2), 5, and 7
from web page.”
1. Read pp. 571-574 and the chapter summary on pp. 575-576. Reading notes are
required, as always.
2. Use a pencil to mark a light “X” through any formula(s) and/or
explanation(s) in the chapter summary on pp. 575-576 that are essentially
worthless.
3. In your own words, write a decent definition of P-value. Do not strive for perfection at this stage. Write your
definition without looking at your textbook or any web-based resources.
4. Write Activity 10.2 on p. 575. You may refer to any resources at your
disposal, as long as you do not copy anyone else’s words.
5. Write a slightly improved definition of power, using the one on p. 576 as a starting point. This time
(unlike what you did in #3), you should refer to the textbook as you rewrite
the definition.
6. Read pp. 583-589, stopping at the end of Example 11.1. Reading notes are
required, as always. However, if you include the formula for df (found in the tan box on p. 587) in your reading
notes, you will be slapped mercilessly.
7. Why would you be slapped mercilessly if you wrote the formula for df (found in the tan box on p. 587) in your reading
notes? Write a brief explanation.
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W 2/25/15
E
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HW due (both
blocks):
1. Read pp. 589-597.
2. Write #11.1, 11.2abc, and 11.4abcd on p. 598. Note: #11.2(c) and #11.4(d) are not in your book but are shown
below.
11.2(c) Explain, using a diagram and some accompanying text, why a commuting
route that has a higher population mean travel time may be preferable to one
that has a lower population mean travel time but a higher sigma. Give at
least three reasons for your answer. At least one of your reasons should
include the word “probability.”
11.4(d) Carry out a test (with all PHASTPC steps, including the S) to
determine if there is convincing evidence that the true mean number of hours
reported to be spent online in a typical week is greater for male teenagers
than for female teenagers. Use a 0.05 significance level.
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Th
2/26/15
F
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No class.
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F 2/27/15
G
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HW due (both
blocks):
1. Read pp. 606-614. Reading notes are required, as always.
2. Write #11.21 on p. 604. Full PHA(S)TPC procedures are required (S
optional).
3. Write #11.25 on pp. 604-605. You can abbreviate your procedures to PHC for
this one, since A, T, and P are already given either in the question or in
the printout.
4. Write #11.29 on p. 615.
5. Write #11.36 on pp. 616-617. Full PHA(S)TPC procedures are required (S
optional).
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