1. Warm Up: Given the normal distribution… Geometry Final Exam scores are 50 students join a rigorous study group to increase their test scores. The program is ran by a teacher earning $200 a session. Is this result significant at the.01 level? (if level not given assume.05) 1

2. Warm Up: 1. Statistics Final Exam scores are normally distributed with 2. 10 students join a rigorous study group to increase their test scores. The group is ran by a teacher earning $500 each 2 hour session. 3. Is this result significant at the.05 level? (if level not given assume.05) 4. Is this result significant at the.01 level? 2

3. Performing significance test (Chapter 10.2) on a Calculator Step 1: Go to STAT  TEST  1:Z-Test Step 2: Data or Stats?  ENTER Step 3:  Calculate gives you the z-score  Draw gives you the graph, z-score and probability Example: re-do the warm up using the calculator Pg.585

4. Practice Pg.586 Exercise 10.56

5. Section 10.3 Making Sense of Statistical Significance AP Statistics

6. Choosing a level of significance (alpha level) How plausible is H 0 ?  Depending on H 0 plausibility, you may choose a smaller alpha to make your point.  If H 0 is very plausible, you will need to have collect “more” evidence to reject it. Example: “You can eat as much as you want and lose weight, as long as you avoid grain products.”  Atkins diet

7. What are the consequences of rejecting H 0 ? If rejecting H 0 would  costs lots of money  possibly cost lives  costs jobs then alpha is usually very small If you want to show the “new thing” is true and the “old thing” is not true you better have a lot of evidence, low alpha level. Example: Global Warming  Rejecting the null would cost more Green energy, expensive cars, etc. to cut down on carbon footprint

8. Fishing for significance Lets look at an example: Diets that make you smarter Let’s say were trying to find a connection between eating habits and intelligence. Choose 40 foods, and assign people to increase the amount of the foods they eat, and see if there are any foods that make people smarter. Of the 40 foods, we find that Peeps and green beans make you smarter with alpha=.05. Is this a problem?

9. Fishing for Significance Yes, this is a problem. When using alpha=.05 we would expect that by pure chance variation we get significant results once every 20 times. With 40 foods being tested, about 2 of the foods would have significant results by pure chance.

10. Assignment 10.57-10.65 odd