2. Chap 1 Section 2

3. Ogives and Timeplots O-What???

4. Ogives Pronouced Oh-Jives An ogive is a relative cumulative frequency graph. Frequency: how often a value is represented Relative: percent Cumulative: less than or equal to Ogive: percentiles

5. Frequency Tables This data set lists the number of books that are on the desks of 50 college students at 8:00 a.m. on Monday morning. Using this data, count how many times each value occurs. Make a tally chart. 351046 7212119 75348 5109147 21057 89141810 16785 3101234 22643 510996

6. Frequency and Relative Frequency Frequency simply means how many times a certain value occurs. Relative frequency means you convert the number of tally marks to a percent of the total.

7. Cumulative Frequency vs. Relative Cumulative Frequency Cumulative frequency, therefore, tells us how many values fall at or below a certain number! Relative cumulative frequency divides that number by the total in the data set to give us a percentile. This tells us the percent of values that fall at or below a certain number! To have your calculator find the cumulative frequency, go to List, OPS, Cumsum(

9. This is an Ogive!!! These are percentiles

10. Turn to page 36. We will work through 1.29 We will work through 1.29

11. Time Plots The time scale is on the horizontal axis. The variable of interest (temperature, stock prices, gasoline prices) is on the vertical axis. Look for trends and an overall pattern.

12. Section 1.2 Comparing Distributions 2005’s Free Response Question #1 part a The back-to-back stem plot below displays the number of calories of food consumed per kg of body weight for each student… a) Write a few sentences comparing the distribution of daily caloric intake ….

13. How it was graded: Part a) was graded Essentially Correct, Partially Correct, or Incorrect E: a student must successfully compare center, shape and spread. Specific numeric values are not required. P: a student must successfully compare 2 of the 3 measures of center, shape and spread. All other responses are graded as Incorrect. Stating “the mean of the rural students’ daily caloric intake is 40.45 while the mean for the urban students is 32.6” is not a COMPARISON and would earn an I.

14. Graph Choices for Comparing Categorical Distributions For two qualitative data sets, a side by side bar graph is effective. Grade