Exam, Calc & Computer Output Tips

1. Exam, Calc & Computer Output Tips Thanks to many colleagues for tips Dr. Davidson Mallard Creek High School

2. For an electronic copy of this presentation, please email me: Lewis.Davidson@cms.k12.nc.us Quick questions – call me at home 704-786-0470

3. 9 Years - Questions & Answers http://www.collegeboard.com/student/testing/ap/statistics/samp.html?stats Or go to http://www.collegeboard.com • Student • AP • Statistics • Sample Questions & Scoring

4. Exam booklet Insert • An insert in the exam booklet contains the questions without the answer spaces • Remove it from the exam booklet and use it for reference • No credit is given for anything written on the insert (the readers do not see it) • Write answers and all your work for each problem in the pages in the exam booklet!

5. Get Familiar with Exam Format • Look at 2011 Exam - (link on previous slide) • Pages 3 – 5:Formulas - understand them! • Pages 11 – 14:Tables - understand them! • What do they mean? • How do we use them?

6. Multiple Choice • Answer every question . (period) • Answer every question . (period) • Answer every question . (period) • Do all work in test book and circle answers there • Only bubble when you are done – but be sure you leave time to bubble. • Please DO YOUR BEST to NOT ERASE!.

7. Free Response Questions • Must move fast & write only what is needed - most kids report not enough time • 1st: Five comprehensive questions (75%) • They usually include different parts of our course • 1st Question: Plan ≤ 10 minutes (often Descriptive) • Next four: average ≈ 12 minutes each 2nd: Investigative Task(25 % of FR Score) • Plan on 25 minutes – Just follow the prompts!

8. Game Plan • Many say 1st read all questions – Dr. D. disagrees. -- “Not enough time”, I say • Consider this approach • Do Q#1: It is usually the easiest & fastest - 10 Minutes MAXIMUM • Work on Q#6 – Investigative task, unless you have no idea what to do. Usually, just follow the prompts EXACTLY 30 Minutes MAXIMUM • Consider Q#2 – 5 in order: Do or skip for now • Say what you know-you may get partial credit

9. The Plays – in EXAM Booklet • Glance at last sentence or a), b), etc requests – get a sense of problem • Start reading from the beginning of the question, but for now just scan long scenario descriptions – now you understand the problem • Now read carefully from the start and underline the key facts you need

10. Free Response Scoring • 1st Readers check for specific attributes specified in the rubrics (0 – 4 points total) • Then Readers holistically consider your demonstrated knowledge & set your score • Unlike Multiple Choice: • Partial Credit is granted! • There are no penalties for wrong answers

11. Free Response Ideas • Write what you best know on the topic • Some work can earn Partial Credit • Note: Blank = zero! • Readers “are on your side” and award points based on work shown • NO“alternate solutions”  give it your best shot! (if 2 solutions, your worst one is scored so cross out worst comments)

12. Readers must read & understand • Be legible! (Dark pencil or pen) • Answers will be copied • Write in good sentences! • Show a logical flow! • Clearly show your work and answer! • Use standard statistical jargon! • The answer space provided has plenty of room for what is expected – use it as a guide!

13. Misc • You can bring two calculators to the exam • Can bring extra batteries _DO IT • Bring at least two sharp # 2 Pencils • Bring a super eraser! -- Note if the scanner can’t read one of your answers, you will not know it!

14. Ten Lessons Learned in 10+ Years as an AP Statistics Exam Reader Daren Starnes The Lawrenceville School dstarnes@lawrenceville.org BFW Publishers April 28, 2009

15. #10: Read the question--twice! 2008 AP Exam, Free Response Question 1 To determine the amount of sugar in a typical serving of breakfast cereal, a student randomly selected 60 boxes of different types of cereal from the shelves of a large grocery store. The student noticed that the side panels of some of the cereal boxes showed sugar content based on one-cup servings, while others showed sugar content based on three-quarter-cup servings. Many of the cereal boxes with side panels that showed three-quarter-cup servings were ones that appealed to young children, and the student wondered whether there might be some difference in the sugar content of the cereals that showed different-size servings on their side panels.

16. #10: Read the question--twice! To investigate the question, the data were separated into two groups. One group consisted of 29 cereals that showed one-cup serving sizes; the other group consisted of 31 cereals that showed three-quarter-cup serving sizes. The boxplots display sugar content (in grams) per serving of the cereals for each of the two serving sizes.

17. #10: Read the question--twice! (a) Write a few sentences to compare the distributions of sugar content per serving for the two serving sizes of cereals.

18. #10: Read the question--twice! 2008 AP Exam, Free Response Question 1 To determine the amount of sugar in a typical serving of breakfast cereal, a student randomly selected 60 boxes of different types of cereal from the shelves of a large grocery store. The student noticed that the side panels of some of the cereal boxes showed sugar content based on one-cup servings, while others showed sugar content based on three-quarter-cup servings. Many of the cereal boxes with side panels that showed three-quarter-cup servings were ones that appealed to young children, and the student wondered whether there might be some difference in the sugar content of the cereals that showed different-size servings on their side panels.

19. #10: Read the question--twice! To investigate the question, the data were separated into two groups. One group consisted of 29 cereals that showed one-cup serving sizes; the other group consisted of 31 cereals that showed three-quarter-cup serving sizes. The boxplots display sugar content (in grams) per serving of the cereals for each of the two serving sizes.

20. #9: Answer the question! (a) Write a few sentences to compare the distributions of sugar content per serving for the two serving sizes of cereals.

21. #8: Don’t shoot yourself in the foot! • Shape • Skewed which way? • “Normal”?! • Center • Mean?! • Spread • Standard deviation?!

22. #7: Avoid calculator speak (1) Binompdf(12,.2,3) = no full credit • Better: P(X = 3) = (12C3)(0.2)3(0.8)9 • OK: binompdf with n = 12, p = .2, k = 3 (2) Normalcdf(90,105,100,5) = no full credit • Better: draw, label, shade Normal curve • OK: normalcdf with low bound = 90, high bound = 1-5, mean = 100, std. dev. = 5

23. #6: Naked answer = no credit • Directions: Show all your work. Indicate clearly the methods you use, because you will be graded on the correctness of your methods as well as on the accuracy and completeness of your results and explanations. From 2008 Exam, FR Question 3 • “Calculate the expected score for each player.” • “Find the probability that the difference in their scores is -1.”

24. #5: Know your inference methods 2008 AP Exam, Free Response Question 5 A study was conducted to determine where moose are found in a region containing a large burned area. A map of the study area was partitioned into the following four habitat types. (1) Inside the burned area, not near the edge of the burned area, (2) Inside the burned area, near the edge, (3) Outside the burned area, near the edge, and (4) Outside the burned area, not near the edge.

25. The study area The figure below shows these four habitat types. The proportion of total acreage in each of the habitat types was determined for the study area.

26. Aerial survey results Using an aerial survey, moose locations were observed and classified into one of the four habitat types. The results are given in the table below.

27. #5: Know your inference methods (a) The researchers who are conducting the study expect the number of moose observed in a habitat type to be proportional to the amount of acreage of that type of habitat. Are the data consistent with this expectation? Conduct an appropriate statistical test to support your conclusion. Assume the conditions for inference are met.

28. #5: Know your inference methods • What percent of students at your school have a MySpace page? • Is there a relationship between students’ favorite academic subject and preferred type of music at a large high school? • VERY-VERY Helpful web site: http://www.ltcconline.net/greenl/java/Statistics/StatsMatch/StatsMatch.htm

29. #4: Don’t skip the investigative task Part B Question 6 Spend about 25 minutes on this part of the exam. Percent of Section II score—25

30. #3: Beware mandatory deductions • Saying “experiment” for an observational study • “Confounding” when there isn’t • Using incorrect symbols: eg statistics in a hypothesis

31. #2: Only use terms and symbols you know • It’s better to explain in your own words than to use a technical term incorrectly • If you’re unsure about notation, use words instead of symbols

32. #1: Don’t write too much • Answer the question asked and only, the qustioned asked; then STOP ! • Space provided is more than enough • Remember the mandatory deduction rule

33. Ten Lessons Learned: Recap #10: Read the question--twice! #9: Answer the question! #8: Don’t shoot yourself in the foot! #7: Avoid calculator speak #6: Naked answer = no credit #5: Know your inference methods #4: Don’t skip the investigative task #3: Beware mandatory deductions #2: Only use terms and symbols you know #1: Don’t write too much

34. Mrs. Lerner’s Top AP Exam Tips • Don’t change an answer unless you have a reason of which you are very sure • State all assumptions & check conditions • Answer all parts of the Free Response questions – Make up an answer you don’t know if needed for the next part • Label and scale all graphs

35. Mrs. Lerner’s Top AP Exam Tips • Don’t give ‘parallel’ solutions on the Free Response questions • Write neatly • Write all conclusions in context • Read all the words (just skimming “long scenario statements”) and understand what the question is asking (usually it is at the end)