General Set up of the General Set up of the examexam

Two SectionsTwo Sections

Multiple ChoiceMultiple Choice 90 minutes90 minutes 40 questions40 questions

Free ResponseFree Response 90 minutes90 minutes 6 questions (5 shorter, 1 longer)6 questions (5 shorter, 1 longer) TopicsTopics

Exploring data (describing patterns and departures Exploring data (describing patterns and departures from patterns)from patterns)

Sampling and experimentation (planning and Sampling and experimentation (planning and conducting a study)conducting a study)

Anticipating patterns (producing models using Anticipating patterns (producing models using probability and simulation)probability and simulation)

Statistical inference (estimating population Statistical inference (estimating population proportions and testing hypotheses).proportions and testing hypotheses).

Multiple ChoiceMultiple Choice

1 point for a correct answer1 point for a correct answer0 for no answer0 for no answerCounts 50% of your gradeCounts 50% of your grade

Free ResponseFree Response

50% of your grade50% of your gradeQuestions 1-5 are 15% each of free Questions 1-5 are 15% each of free

response graderesponse gradeQuestion 6 is 25% of free response Question 6 is 25% of free response

gradegradeScore is a 0-4Score is a 0-4

Tips for Writing Free Tips for Writing Free Response Questions on Response Questions on the AP Statistics Examthe AP Statistics Exam

It should be obvious…It should be obvious…

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

Common Task: ChooseCommon Task: Choose

If you are asked to choose between If you are asked to choose between two things (fuel additive A or fuel two things (fuel additive A or fuel additive B), state why you would additive B), state why you would choose one AS WELL AS why you choose one AS WELL AS why you would NOT choose the other.would NOT choose the other.

However , be careful not to contradict However , be careful not to contradict yourself!yourself!

Common Task: CompareCommon Task: Compare

If you are asked to compare, make less If you are asked to compare, make less than/greater than statements.than/greater than statements.

Compare like things. Never compare a Compare like things. Never compare a median of one distribution to the 1st median of one distribution to the 1st quartile of another. Instead, compare quartile of another. Instead, compare the median of distribution A to the the median of distribution A to the median of distribution B.median of distribution B.

AP Questions often ask you to compare AP Questions often ask you to compare one-variable distributions. You’ll need to one-variable distributions. You’ll need to compare center, shape and spread.compare center, shape and spread.

Common Task: Test of Common Task: Test of SignificanceSignificance

Hypothesis Test rubrics generally look for Hypothesis Test rubrics generally look for four components:four components:

State the hypotheses with the correct State the hypotheses with the correct symbols. Define any subscripts.symbols. Define any subscripts.

Identify (by NAME or by FORMULA) a test-Identify (by NAME or by FORMULA) a test-statistic. State statistic. State andand check the assumptions. check the assumptions.

Calculate the value of the test-statistic. Calculate the value of the test-statistic. Calculate the p-value and compare it to alpha. Calculate the p-value and compare it to alpha. Reject or fail to reject the null hypothesis. Reject or fail to reject the null hypothesis.

State your conclusion in words in the context State your conclusion in words in the context of the problem.of the problem.

Writing TipsWriting Tips

Be clear, brief, and explicit.Be clear, brief, and explicit. If you ramble on and on, you’re likely If you ramble on and on, you’re likely

to contradict yourself. Plus, when a to contradict yourself. Plus, when a student is brief, it is clear that he/she student is brief, it is clear that he/she knows what the question is asking and knows what the question is asking and how to answer it.how to answer it.

Writing TipsWriting Tips

Never contradict yourself.Never contradict yourself. NEVER write calculator commands.NEVER write calculator commands.

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

Remember binomial distribution?Remember binomial distribution?

Writing TipsWriting Tips

Be careful about strong language.Be careful about strong language. One sample design question asked One sample design question asked

why we randomly allocate subjects to why we randomly allocate subjects to treatment groups. If students stated treatment groups. If students stated that random allocation ELIMINATES that random allocation ELIMINATES bias, they were given NO credit.bias, they were given NO credit.

You never PROVE anything!!!You never PROVE anything!!!

Writing TipsWriting Tips

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

Don’t use no double negatives.Don’t use no double negatives. I fail to reject that I don’t believe that I fail to reject that I don’t believe that

the data are not independent.the data are not independent.

Common Student ErrorsCommon Student Errors

Realizing that when the directions say “Give Realizing that when the directions say “Give appropriate statistical evidence to support your appropriate statistical evidence to support your conclusion” or “Justify, using statistical evidence” conclusion” or “Justify, using statistical evidence” students are asked to conduct FORMAL students are asked to conduct FORMAL hypothesis tests.hypothesis tests.

Realizing that when you write the words “on Realizing that when you write the words “on average” that you’re referencing the mean.average” that you’re referencing the mean.

Using non-statistical words to convey a statistical Using non-statistical words to convey a statistical concept.concept. The graph is “even.” ??? Do they mean uniform? The graph is “even.” ??? Do they mean uniform?

Symmetric? Normal?Symmetric? Normal? The residual plot is “half above and half below.” I think The residual plot is “half above and half below.” I think

they meant they meant uniformly scattereduniformly scattered..

Common Student ErrorsCommon Student Errors

The amount of space left for students to The amount of space left for students to answer the question is NOT an indication of answer the question is NOT an indication of how much you should write.how much you should write.

Expected value = mean.Expected value = mean. When stating assumptions, saying the data When stating assumptions, saying the data

are normal or the distribution is normal is are normal or the distribution is normal is not correct.not correct. The correct assumption is that the population is The correct assumption is that the population is

distributed normally. We check that assumption distributed normally. We check that assumption by looking at the distribution of the sample data.by looking at the distribution of the sample data.

Common Student ErrorsCommon Student Errors

Students tend to confuse skewed Students tend to confuse skewed right and skewed left.right and skewed left.

Students tend to confuse symmetric Students tend to confuse symmetric with approximately normal.with approximately normal.

Students tend to list everything they Students tend to list everything they know and hope that part of it is know and hope that part of it is correct. This is called a “parallel correct. This is called a “parallel solution.” The graders will grade the solution.” The graders will grade the weakest of the solutions.weakest of the solutions.

Common Student ErrorsCommon Student Errors

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

Common TopicsCommon Topics

Exploratory Data AnalysisExploratory Data AnalysisOne-variable dataOne-variable data

Descriptive statistics: Center, Shape, Descriptive statistics: Center, Shape, SpreadSpread

Two-variable dataTwo-variable dataCorrelation, regression, residual plots, Correlation, regression, residual plots,

coefficient of determinationcoefficient of determinationHypothesis TestsHypothesis TestsProbabilityProbabilityExperimental DesignExperimental Design

In the end…In the end…

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

know.know.

Some college creditSome college credit

UNC Chapel Hill… 3 or moreUNC Chapel Hill… 3 or moreNC State… 3 or moreNC State… 3 or moreUNCC… 3 or moreUNCC… 3 or moreAppalachian… 3 (one class), 4 or 5 Appalachian… 3 (one class), 4 or 5

(two classes)(two classes)

CalculatorCalculator

You can use your own (no higher You can use your own (no higher than Ti-89)than Ti-89)

Take extra batteriesTake extra batteries I will send extras.I will send extras.Make sure you have Diagnostic On… Make sure you have Diagnostic On…

Let’s do this now.Let’s do this now.Your calculator will not be cleared.Your calculator will not be cleared.

On the day of the testOn the day of the test

Take pencils!!!!Take pencils!!!!Take your calculatorTake your calculatorGet some rest the night beforeGet some rest the night beforeGet to your testing site at 11:30Get to your testing site at 11:30

Do not schedule work for before 4:00Do not schedule work for before 4:00Do your best!Do your best!

Materials for ReviewMaterials for Review

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

Students Students Borrow an AP Review BookBorrow an AP Review BookCheck out the links on my websiteCheck out the links on my websitehttp://apcentral.collegeboard.com/http://apcentral.collegeboard.com/

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