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# General Set up of the exam - PowerPoint PPT Presentation

General Set up of the exam. Two Sections. 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)

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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

• 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

It should be obvious… Statistics Exam

• 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.

Common Task: Test of Significance Statistics Exam

• 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.

Writing Tips Statistics Exam

• 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.

Writing Tips Statistics Exam

• NEVER write calculator commands.

• Never? Never. Never ever. Not even once. Period.

• Remember binomial distribution?

Writing Tips Statistics Exam

• 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!!!

Writing Tips Statistics Exam

• Do not use pronouns!

• “It is higher.” WHAT is higher?

• Don’t use no double negatives.

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

• Common Student Errors Statistics Exam

• 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.

Common Student Errors Statistics Exam

• 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.

Common Student Errors Statistics Exam

• 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.

Common Student Errors Statistics Exam

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

Common Topics Statistics Exam

• Exploratory Data Analysis

• One-variable data

• Descriptive statistics: Center, Shape, Spread

• Two-variable data

• Correlation, regression, residual plots, coefficient of determination

• Hypothesis Tests

• Probability

• Experimental Design

In the end… Statistics Exam

• It’s not what you know.

• It’s what you can SHOW that you know.

Some college credit Statistics Exam

• UNC Chapel Hill… 3 or more

• NC State… 3 or more

• UNCC… 3 or more

• Appalachian… 3 (one class), 4 or 5 (two classes)

Calculator Statistics Exam

• 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.

On the day of the test Statistics Exam

• Take pencils!!!!

• Get some rest the night before

• Get to your testing site at 11:30

• Do not schedule work for before 4:00