"Every new body of discovery is mathematical in form, because there is no other guidance we can have." -- (Charles Darwin) Persian-born Omar Khayyam (1048-1131) was both a poet and a mathematician. He is the author of a collection of poetry titled Rubaiyat. He contributed much to mathematics, including finding geometrical solutions for cubic equations and calendar reform, suggesting a cycle of 33 years that included 8 years with 366 days. Ever the poet, his reforms are referenced in the Rubaiyat: Ah, but my Computations, People say, Reduced the Year to better reckoning? - Nay, 'Twas only striking from the Calendar Unborn Tomorrow, and dead Yesterday. Why was Herkimer always tired on April 1? Answer: He had just finished a March of 31 days. Things Herky would like to know: Why do you drive on a parkway and park in a driveway? If a tree falls in a forest and no one is around to see it, do the other trees make fun of it? ASSIGNMENT #23 Reading: Review Chapter 3, as necessary Exercises: Do Test 3A (handout in class) as a review exercise.

You are working with ideas from Chapter 3.

Test 3A represents an excellent review of the keyideas and concepts presented in Chapter 3. Here are just a fewimportant points:

• r2 > 0 does not necessarily mean that r > 0.
• Don't confuse slope of least squares regression line with the correlation coefficient. Understand that if the slope of a LSRL is close to 1 (for instance), the coefficient of correlation could be close to 0.
• Association does not imply causation.
• The terms influential point and outlier are not interchangeable. While there can be some overlap, the terms do reference different things. Points that are outliers in the x-direction are often influential.
• A residual plot displays deviations for a prediction model, which may or may not be a line.
• The sum of a residual row or column is zero.

=======================================

Text:
The Practice of Statistics, by Yates, Moore, McCabe. New York,W.H. Freeman and Company, 1999. (ISBN 0-7167-3370-6)

Supplemental books:
The Cartoon Guide to Statistics, by Gonick and Smith. NewYork, HarperCollins Publishers, 1993. (ISBN 0-06-273102-5)
How to Lie with Statistics, by Darrell Huff. New York, W.W.Norton & Company, 1982 (ISBN 0-393-09426-X)