Swarthmore College, Spring 2006
Stat 11 - Statistical Methods

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jump to course documents --- course information (or see syllabus) --- course-catalog entry for Stat 11 --- schedule
Textbook website: http://www.whfreeman.com/ips or try this URL.

This is the home page for Statistics 11 (both sections).

5/10/06 - By popular demand, here are some Excel regression worksheets:
TwoRegressions.xls - global warming and field hockey crowds
a1a.xlsData, random regressions, (lots of) random junk re. Presidential elections
crickets-20Apr.xlsCrickets again (also with lots of junk on extra pages

5/7/06 - Here are some sample problems, with solutions, for a last-minute review. THESE ARE NOT COMPREHENSIVE. Don't even think of limiting your review to these problems.
Word version: Samples.doc (7 pages, with MathType)
HTML version: Samples.htm
The best lists of topics are still the "what's on the exam" sheets for exams 1 and 2. Beyond those topics, the final exam covers one-way and two-way tables and the corresponding chi-square tests, and multiple regression to the extend we covered it. For multiple regressions: Section 10.1 is perhaps worth reading, but isn't required and is only approximately what we covered.


Click here for full-sized version (section 1).


Click here for full-sized version (section 2).

4/30/06 - FWIW, Here is the PowerPoint checklist of review topics, from class 4/24 through 4/28.

4/18/06 - About the exam: You're invited (as "homework 10") to write up correct solutions to Exam #2, for up to half the face value of any points you lost. Use your own paper, and clearly indicate the problem numbers that go with your solutions. Don't turn in solutions to problems for which you already got full credit. You MAY use any tools references and you MAY consult with others including other students, but you must write up your own solutions. These are due Friday 4/21, but I'll accept them up to the last day of classes.

4/18/06 - Here are the solutions to homework 9 (the chi-square problems).

4/12/06 - Here are... 11homework9.doc -- Homework 9, including the problem added today. WORD, two pages.
dogscats.doc -- worksheet from class 4/12 (WORD, 1 page)

4/2/06 - Also, if anyone is still looking for the reference sheet, here it is:
11exam2cover.doc - front page of exam 2
You'll also have the "z table" and Table D.

4/1/06 - Here are the solutions to homework sets 7 and 8.
11solutions7.doc - solutions 7, Word version
11solutions7.htm - solutions 7, html version
11solutions8.doc - solutions 8, Word version
11solutions8.htm - solutions 8, html version

3/30/06 - Alert to the first section: On Friday I'll ask you for a bunch of (subjective) 90% confidence intervals. The second section, like almost everyone who does this exercise, chose intervals that were way too small. On average, they got about 40% of the questions "right" (in the sense that 40% of their intervals contained the truth). You are getting multiple warnings not to make this mistake. Will it make a difference?

3/30/06 - I have corrected the techniques document. To get the p-value for a "t" statistic, the Excel function is
=TDIST ( |t|, df, 1 or 2 )
and NOT 1 - TDIST(...). Oddly, the NORMSDIST function always gives left tails, while the TDIST function always gives right tails (and insists on a non-negative first argument). All links now point to the corrected version.

3/29/06 - Two documents for class today:
11techniques.doc -- summary of confidence-interval and hypothesis-test techniques from chapters 6-8 (Word with MathType, 3 pages)
11preexam2.doc -- "What's on the Exam" sheet #2 (Word with MathType, 3 pages)
We'll do Ed Capen's confidence-interval demonstration today, if we have time.

3/27/06 - The next exam is MONDAY, APRIL 3, and will cover (roughly) material from Chapter 8.

HERE'S HOMEWORK 8 (due March 31): Problems 7-53 (no essays and no 1-sided test; just do the 2-sided test), 7-122 (all), 8-11, 8-13, 8-23, 8-5(a), 8-6(a), 8-35 (the last three are one project; use the SE's from #5 and #6 for #35), 8-36 (with a pooled-p test for the difference of proportions.

3/21/06 - There's another COOKIE FRIDAY this week, 3:30pm Friday, in the math/stat department living room!

3/21/06 - NO EXAM THIS FRIDAY. The next exam will be Friday, March 31, or (more likely) Monday, April 3, and will cover (roughly) material through chapter 8. More as we get closer.

3/20/06 - There's homework for Friday! Here's homework #7 in the Word version and the html version. Also, Solutions #6 is posted below.

Also, here is the PowerPoint presentation on hypothesis tests from class today. I'm still revising the second part, so it might be good to wait for the revisions.

3/20/06 - Solutions #6 and homework #7 are posted below.

3/13/06 - Here's the PowerPoint presentation from class this week. Homework 6 is posted below.

3/5/06 - Solutions to homework #5 are posted below.

Here is a link to John Zogby's polling site where you can find the press release describing the poll of soldiers in Iraq. Also, here is the "mystery pollster's" site with (very) extensive commentary on the poll. Scroll down; the first Zogby-poll entry is from February 28.

2/27/06 - Here is homework #5, due 3/3/06: both Word version and web version. It includes the three problems on estimating proportions that were handed out last Friday, and a few problems from Chapter 4.

Also, here is a completed version of the handout from class 2/27.

2/17/06 - Solutions to hw #4 are posted below.

2/16/06 - Here's the whats-on-the-exam sheet in html form, and here it is as a 4-page Word document. (As usual, the Word version is more reliable, but the html version may be easier to read on the web.)

2/12/06 - THE FIRST EXAM IS IN CLASS ON MONDAY, FEBRUARY 20. People with serious conflicts should let me know by Wednesday, Feb. 15. It will cover Chapters 1, 2, 3, and the first ideas of Chapter 4 (reaching as far as this Friday's homework and what we cover in class through Feb. 15).

Homework 4 is posted below. So is this peculiar spreadsheet, which I'll try to use in class tomorrow if I don't get cold feet.

2/12/06 - Solution set 3 is posted below.

2/7/06 - Homework 3 is posted under course documents, below. Here is a translation table:
5th edition vs. 4th edition:
5th ed4th ed
2.142.10
2.322.23
2.552.49
2.582.52
2.792.75
3.6, 3.7   Not in 4th
"Problem A"  based on 2.54

2/3/06 - Here are solutions to hw #2. (See below for the Word version.)

Here's a link to the "Correlation Game:"
http://www.stat.uiuc.edu/courses/stat100/java/GCApplet/GCAppletFrame.html
Click on "New Plots" to start.

Finally, here's a link to the full paper on fast recognition of faces:
http://pantheon.yale.edu/~cm355/papers/EMOTION05.pdf

2/1/06 - Homework 2 was missing from the "course documents" list below, but it's there now. So are today's slide show and the raw "crickets" data. Finally, here is a link to the Stat-1 text's website with the applet on regression lines.

1/30/06 - Slides from today (Monday 1/30) are posted below, along with the "z table" and the cigarettes example. Wednesday we'll talk about regression lines (Sec. 2.3-2.5).

About the mini-exam: More than half of the papers had perfect scores, which is good, but I hope that those who didn't will make sure they can answer similar questions on the next exam --- most specifically, what fraction of values of some normally distributed variable are between ___ and ___? The miniexam is here; the correct answers were 95% (or 95.44997361%), 92% (or 91.92433408%), and --- for the guessed standard deviation --- anything from 6 to 18. (The figure was based on data with an SD of exactly 10, but given the picture you had, 7 or 8 may have been a better guess.)

1/27/06 - The solution set for hw 1 is below (under "course documents").

1/26/06 - Here's a hasty set of instructions for making histograms in Excel using the FREQUENCY function. The examples we built in class are here: Section 1's example and Section 2's example.

1/25/06 - About homework 1: Problem 4d should be, "How do you reconcile your answers to (b) and (c)?" Maybe you have answered both questions in a consistent way, and you don't have anything to reconcile. But if the principle behind your answer to (b) didn't work for (c), you should explain.

The last problem (two problems, really, 1.85 and 1.86) involve normal distributions, which we didn't get to in class. You'll need to read ahead to page 71 for the "68-95-99.7 rule." The applet referred to in 1.85 can be found by going to the text web site (see above) and clicking on "statistical applets."

4th edition vs. 5th edition:
5th ed4th ed
1.21.2(p. 22)
1.19, 1.20, 1.21     1.17, 1.18, 1.19 (p. 26-27)
1.31Not in 4th?
1.341.27 (p. 30)
1.411.41 (p. 55)
1.85, 1.861.84, 1.82 (p.86)

1/23/06 - I have added a link, above, to the textbook's website. Some (all?) of the material duplicates the material on the CD that came with the book. Using either source, try the "means and medians" applet --- it's entertaining for a few minutes. What happens to the mean and median when you drag a point across the scale from left to right? Does it depend on whether there is an odd number of points or an even number?

There were a few copies of the textbook at the bookstore on Friday, but they sold out again. The book czar says more copies will arrive this week.

Also: Here is a link to the press release about the face-recognition study described by Ira Flatow. I'm still looking for the article itself. Note that my skepticism is based on experience with other research; I don't mean to imply a negative judgment of Olsen and Marshuetz, who may have discovered something surprising.

Here's homework 1 Also, today's PowerPoint slides are linked to below.

1/19/06 - The schedule has been upgraded from "mockup" to "draft".

1/17/06 - Here are the power-point slides from class 1/16.
ABOUT THAT ASSIGNMENT FOR WEDNESDAY --- It's really optional, and the prizes won't amount to much. But, find what you can in the way of GOOD, BAD, or INTERESTING graphical displays of single categorical variables. Bad examples are best if they come from prestigous publications; then we can all snort at them and feel smugly superior.
(Look for other good, bad, and interesting statistical graphics, too; we'll look at them Friday and Monday.


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Course documents:        (back to top)

Note: Homework 8 is posted at the top of the page.

ht.ppt -- ppt slides on hypothesis tests, used in class starting 3/20/06 (subject to revision)

11homework7.doc -- homework 7, 3/20/06, due 3/24/06, Word, 1 page
       11homework7.htm -- homework 7, html version

ci.ppt -- ppt slides on confidence intervals, used in class starting 3/13/06

11homework6.doc -- homework 6, 3/13/06, due 3/17/06, Word, 2 pages
       11homework6.htm -- homework 6, html version
       11solutions6.doc -- solutions 6, 3/20/06, Word, 5 pages
       11solutions6.htm -- solutions 6, 3/20/06, html version

11notes022706.doc -- worksheet from class 2/24/06 and 2/27/06 (filled in), Word, 1 page

11homework5.doc -- homework 5, as revised 2/27/06, due 2/2/06, Word, 2 pages
       11homework5.htm -- homework 5, html version
       11solutions5.doc -- solutions 5, 3/5/06, Word, 4 pages
       11solutions5.htm -- solutions 5, 3/5/06, html version

11preexam1.doc -- Pre-exam checklist for exam 1, 2/16/06, 4-page Word document
11preexam1.htm -- Pre-exam checklist in html form

RandomWalk.xls -- Spreadsheet intended for class on 2/13/06.

11homework4.doc -- homework 4, 2/13/06, due 2/17/06, Word, 1 page
       11homework4.htm -- homework 4, html version
       11solutions4.doc -- solutions 4, 2/17/06, Word, 3 pages
       11solutions4.htm -- solutions 4, 2/17/06, html version

11homework3.doc -- homework 3, 2/6/06, due 2/10/06, Word, 1 page
       11homework3.htm -- homework 3, html version
       11solutions3.doc -- solutions 3, 2/10/06, Word, 3 pages
       11solutions3.htm -- solutions 3, 2/10/06, html version

11homework2.doc -- homework 2, 1/27/06, due 2/3/06, Word, 2 pages
       11solutions2.doc -- solutions 2, 2/3/06, Word, 3 pages
       11solutions2.htm -- solutions 2, 2/3/06, html version

Stat11-1Feb06.ppt -- ppt slides from class 2/1: regression lines.
crickets-1Feb.xls -- raw cricket data from class 2/1.

Stat11-30Jan06.ppt -- ppt slides from class 1/30: scatterplots and correlation.
cigarettes.xls -- cigarettes example from class 1/30 (Excel)

ztable.doc -- normal distribution table (Word, 1 page)
HowToHistogram.htm -- hasty instructions for making a histogram with Excel, 1/26/06. Also examples from class: Sec1-Jan25.xls and Sec2-Jan25.xls.
Stat11-20Jan06.ppt -- ppt slides from class 1/20 and 1/23: mean / median / percentiles / box plots / standard deviation / standardizing a variable.

11homework1.doc -- homework 1, 1/20/06, due 1/27/06, Word, 2 pages
       11solutions1.doc -- solutions 1, 1/27/06, Word, 4 pages
       11solutions1.htm -- solutions 1, 1/27/06, html version

Stat11-16Jan06.ppt -- ppt slides from class 1/16: data tables, kinds of variables, some frequency tables (=distributions).
11questionairre.doc --- questionnaire, WORD, 1 page
11survey.doc --- anonymous survey, WORD, 1 page 11Schedule.htm or 11Schedule.xls -- schedule (11/13/05 mockup)
11CourseInfo.html -- syllabus (11/13/05 draft)


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Course Info:        (back to top)

Section 1: Science Center 181, MWF  9:30-10:20 am.
Section 2: Science Center 181, MWF 10:30-12:20 am.

Instructor:   Walter Stromquist
   Office: Science Center 159.
   Office hours: Tuesday and Friday, 1:30 - 4:00 pm.
   Email: wstromq1@swarthmore.edu
   Phone: Cell 610-220-4382 (ok to leave messages).
   Office phone 610-690-6827 (please don't leave messages).
   For snow emergencies on class days, call office phone after 9:00am.

Text: Moore and McCabe, Introduction to the Practice of Statistics, 5th edition, W. H. Freeman, ISBN 0-7167-6400-8. This is a new edition; the 4th edition was used in the fall. The bookstore will probably have the 5th edition by January 23.

Software: TBD. A calculator will help, and can be used on exams.

Web site:    http://www.swarthmore.edu/NatSci/wstromq1/stat11/index.html

Course requirements:
  Homework and short quizzes (about 15% of grade) - homework due about weekly. Collaboration on homework is encouraged but you must prepare your own answers.
  Two in-class exams (25% each) - Maybe about Feb. 17 and Mar. 24.
  Final exam (35%)
  No projects this semester.

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