Please visit the website for the textbook to take a practice quiz before the test on Thursday, 11/3.
http://bcs.whfreeman.com/tps3e/default.asp?s=&n=&i=&v=&o=&ns=0&uid=0&rau=0
October 28, 2011
We began Chapter 2 today with an investigation into standardizing variables. To standardize we find the difference between the observed value and the mean, then we divide by the standard deviation. THis gives us a z-score, which tells us how far in standard deviations a point is away from the mean (and the direction). Z-scores below -3 or above 3 are rare. Z-scores between -1.5 and 1.5 are very common.
We looked at the Normal Probability Plot on the calculator. If the graph on the NPP is relatively straight, then the data look like they are approximately Normally distributed. If the NPP is curvy, then we doubt that they are Normal.
Finally, to compare two measures that have different scales, we standardize the values. For instance, is a 32 on the ACT a worse score than a 1000 on the SAT??? After all, 32 is less than 1000! No, we would standardize the values or turn them into percentile scores to compare these two different measures.
HW due Tuesday: 2.3, 2.4, 2.7, 2.12, 2.13, 2.20, 2.29, 2.30, 2.32, 2.34, 2.40, 2.54, 2.55, 2.56
Key concepts: 68-95-99.7 rule (Empirical rule), Chebyshev's inequality, z-score, percentile
HW due Monday: problem 1 from the 2011 exam. It was handed out in class.
Tuesday, November 1, 2011
We had a not-a-quiz today over some of the skills from this chapter. Practice working problems like these and showing your work.
Download Not a quiz - Normal and density skills
This article shows the application of standardization in curving grades.
Download Score Normalization as a Fair Grading Practice
Read through Chapter 2. Look for key concepts and anything we haven't covered in class. Work some of the problems we did not assign. Answer to the odds are in the back of the book.
Download Chapter 2 Textbook Companion
Visit the textbook website to take the online quiz for Chapter 2.
