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General Set up of the exam

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General Set up of the exam

- Multiple Choice
- 90 minutes
- 40 questions

- Free Response
- 90 minutes
- 6 questions (5 shorter, 1 longer)
- Topics
- Exploring data (describing patterns and departures from patterns)
- Sampling and experimentation (planning and conducting a study)
- Anticipating patterns (producing models using probability and simulation)
- Statistical inference (estimating population proportions and testing hypotheses).

- 1 point for a correct answer
- 0 for no answer
- Counts 50% of your grade

- 50% of your grade
- Questions 1-5 are 15% each of free response grade
- Question 6 is 25% of free response grade
- Score is a 0-4

Tips for Writing Free Response Questions on the AP Statistics Exam

- Read the question. Answer the question. No more, no less.

- If you are asked to choose between two things (fuel additive A or fuel additive B), state why you would choose one AS WELL AS why you would NOT choose the other.
However , be careful not to contradict yourself!

- If you are asked to compare, make less than/greater than statements.
- Compare like things. Never compare a median of one distribution to the 1st quartile of another. Instead, compare the median of distribution A to the median of distribution B.
- AP Questions often ask you to compare one-variable distributions. You’ll need to compare center, shape and spread.

- Hypothesis Test rubrics generally look for four components:
- State the hypotheses with the correct symbols. Define any subscripts.
- Identify (by NAME or by FORMULA) a test-statistic. State and check the assumptions.
- Calculate the value of the test-statistic. Calculate the p-value and compare it to alpha. Reject or fail to reject the null hypothesis.
- State your conclusion in words in the context of the problem.

- Be clear, brief, and explicit.
- If you ramble on and on, you’re likely to contradict yourself. Plus, when a student is brief, it is clear that he/she knows what the question is asking and how to answer it.

- Never contradict yourself.
- NEVER write calculator commands.
- Never? Never. Never ever. Not even once. Period.
- Remember binomial distribution?

- Be careful about strong language.
- One sample design question asked why we randomly allocate subjects to treatment groups. If students stated that random allocation ELIMINATES bias, they were given NO credit.
- You never PROVE anything!!!

- Do not use pronouns!
- “It is higher.” WHAT is higher?

- I fail to reject that I don’t believe that the data are not independent.

- Realizing that when the directions say “Give appropriate statistical evidence to support your conclusion” or “Justify, using statistical evidence” students are asked to conduct FORMAL hypothesis tests.
- Realizing that when you write the words “on average” that you’re referencing the mean.
- Using non-statistical words to convey a statistical concept.
- The graph is “even.” ??? Do they mean uniform? Symmetric? Normal?
- The residual plot is “half above and half below.” I think they meant uniformly scattered.

- The amount of space left for students to answer the question is NOT an indication of how much you should write.
- Expected value = mean.
- When stating assumptions, saying the data are normal or the distribution is normal is not correct.
- The correct assumption is that the population is distributed normally. We check that assumption by looking at the distribution of the sample data.

- Students tend to confuse skewed right and skewed left.
- Students tend to confuse symmetric with approximately normal.
- Students tend to list everything they know and hope that part of it is correct. This is called a “parallel solution.” The graders will grade the weakest of the solutions.

- You need to know the difference between taking a simple random sample and randomly allocating subjects to treatment groups.

- Exploratory Data Analysis
- One-variable data
- Descriptive statistics: Center, Shape, Spread

- Two-variable data
- Correlation, regression, residual plots, coefficient of determination

- One-variable data
- Hypothesis Tests
- Probability
- Experimental Design

- It’s not what you know.
- It’s what you can SHOW that you know.

- UNC Chapel Hill… 3 or more
- NC State… 3 or more
- UNCC… 3 or more
- Appalachian… 3 (one class), 4 or 5 (two classes)

- You can use your own (no higher than Ti-89)
- Take extra batteries
- I will send extras.
- Make sure you have Diagnostic On… Let’s do this now.
- Your calculator will not be cleared.

- Take pencils!!!!
- Take your calculator
- Get some rest the night before
- Get to your testing site at 11:30
- Do not schedule work for before 4:00
- Do your best!

- http://apcentral.collegeboard.com/apc/members/exam/exam_tips/4073.html#name4
- Click on AP Statistics Exam Tips for Students

- Borrow an AP Review Book
- Check out the links on my website
- http://apcentral.collegeboard.com/apc/members/exam/exam_information/8357.html