Today’s Agenda

1. Today’s Agenda Group Activity Notes on Conditional Probabilities Late Work? Grade Questions?

2. Take out a ½ sheet of paper to answer the following questions on. NO NAMES PLEASE Have you ever been bullied/harassed? Have you ever been the bully/harasser? Be sure to number your answers and answer BOTH of the questions. Thank you.

3. Tally Time…(Do on a new sheet of your own paper) • Question 1: Have you ever been bullied/harassed? • Question 2: Have you ever been the bully/harasser?

4. Organize your data Question 1: Been Bullied/harassed? Question 2: Bullied/harasser

5. Organize your data Question 1: Been Bullied/harassed? Question 2: Bullied/harasser

6. Notes: Marginal Relative Frequencies • Marginal totals: Totals for each row or column. • For example… the total # of students that said yes to being bullied. • Marginal Relative Frequencies (fancy terms for…): Estimated probability of each event happening. • For example… our estimate of the probability that any student at Park High may have been a bully at some time would be… MRF = (# of students that said they have been a bully) / (total # of students in our class)

7. Marginal Relative Frequencies[fill in the final row and column] Question 2: Bullied Question 1: Been Bullied?

8. Lesson 8 Assignment • Answer the following questions using the information gathered at the beginning of class: • How many students answered “yes” to being bullied or harassed? • How many students answered “yes” to being the bully or harasser? • How many students answered “yes” to both questions?

9. Questions Continued… • What do the different marginal relative frequencies tell us about our class? About high school students in general? • If the total enrollment at Park High is 1800 students, approximately how many of them would you expect to have been harassed or bullied?

10. Joint Relative Frequencies • Joint Frequency: Totals in each individual box in the body of the chart (the little joints that make up the totals). • Joint Relative Frequency: Used as an estimated probability to show the % of students that may be in each individual situation. For example… JRF = (# of students that said yes to both questions)/(total # of students)

11. Assignment Continues… 6. Write out the 4 joint relative frequencies for your chart: ie… • % of students that said “yes” to both questions = • % of students that said “no” to both questions = • % of students that said “yes” to bullying, but “no” to being bullied = • % of students that said “no” to bullying, but “yes” to being bullied = 7. Out of Park’s 1800 students approximately how many of them have been a bully as well as been a person on the receiving end? 8. Approximately how many have never been bullied and never been a bully? 9. Is there any relationship between those that have been bullied and whether or not they have also taken part in being a bully?

12. Conditional Relative Frequency • Conditional Relative Frequency/Probability: Look at one part of a question or chart (one row or one column) and base all relative frequencies (probabilities) off of that row or columns total. a)Set a condition: • Only looking at Bullies • Only looking at students that said Yes to ever being bullied • Etc… • For example look at all of the Yeses for being bullied: P(you have been a bully knowing that you have been bullied) = (# from that ‘joint’)/(Total # of students that have been bullied)

13. Conditional Rel. Frequency Assignment • White books: Page 68 – 69: 8 – 9 • Summary of Conditional Probability: • Page 70-71: 10 & 11 • make both charts • List all different Relative Frequencies for each (even if not asked for) • Marginal Relative Frequencies • Joint Relative Frequencies • Conditional Relative Frequencies