AP Statistics Exam Hints

AP Statistics Exam AP Statistics Exam HintsHints

Exam FormatExam Format

The AP Statistics Exam is three hours The AP Statistics Exam is three hours long.long. (1) 90-minute multiple-choice section(1) 90-minute multiple-choice section

(2) 90-minute free-response section (2) 90-minute free-response section

Each section is 50% of your overall Each section is 50% of your overall grade.grade.

Exam FormatExam Format

Multiple Choice SectionMultiple Choice Section40 questions40 questions

Free ResponseFree Response5 open-ended questions 5 open-ended questions 1 investigative task involving more 1 investigative task involving more

extended reasoning (Give yourself extended reasoning (Give yourself at at leastleast 25 minutes) 25 minutes)

The EXAMThe EXAMWhat you are allowed to use:What you are allowed to use:

Tables (the same ones in your textbook)Tables (the same ones in your textbook) Formula sheetsFormula sheets Calculator Calculator

Note: You are Note: You are not permittednot permitted to have programs to have programs in your calculator that upgrade the functionality in your calculator that upgrade the functionality beyond the statistical features found on newer beyond the statistical features found on newer approved models.approved models.

Scoring of the Free ResponseScoring of the Free Response Evaluation of student responses on the Evaluation of student responses on the

free response section reflects a dual free response section reflects a dual importance.importance. Statistical KnowledgeStatistical Knowledge Good CommunicationGood Communication

Scored “holistically”Scored “holistically” ““Complete package”Complete package” After looking at the details of your response, After looking at the details of your response,

the reader makes a judgment about the the reader makes a judgment about the overall overall quality of the response.quality of the response.

Scoring FRQs – Scoring RubricScoring FRQs – Scoring Rubric

The Scoring Guidelines – 0 to 4 The Scoring Guidelines – 0 to 4 numerical scalenumerical scale

Each number is associated with a Each number is associated with a level of qualitylevel of quality in the response. in the response.

Scoring FRQs – Scoring RubricScoring FRQs – Scoring Rubric

4 – 4 – CompleteCompleteShows complete understanding Shows complete understanding of the problem’s statistical of the problem’s statistical components and provides a components and provides a clear, organized, and complete clear, organized, and complete explanation, using correct explanation, using correct terminology, of what was done terminology, of what was done and why.and why.

Scoring of the Free ResponseScoring of the Free Response

3 - 3 - SubstantialSubstantial Shows substantial Shows substantial

understanding of understanding of the problem’s the problem’s statistical components statistical components and and provides a clear but not perfectly provides a clear but not perfectly organized explanation, using organized explanation, using correct correct terminology, of what was terminology, of what was done and done and why, but explanation why, but explanation may be slightly may be slightly incomplete.incomplete.


2 – 2 – DevelopingDevelopingShows some understanding of the Shows some understanding of the problem’s statistical components problem’s statistical components and provides some explanation of and provides some explanation of what was done, but the explanation what was done, but the explanation may be vague and difficult to may be vague and difficult to interpret and terminology may be interpret and terminology may be somewhat inappropriate.somewhat inappropriate.


1 – 1 – MinimalMinimalShows limited understanding of the Shows limited understanding of the problem’s statistical components by problem’s statistical components by failing to identify important failing to identify important components; provides minimal or components; provides minimal or unclear explanation of what was done unclear explanation of what was done or why it was done, and explanation or why it was done, and explanation may not match the presented may not match the presented solution.solution.

AP ScoringAP Scoring

11stst section - Multiple Choice section - Multiple Choice 40 questions – 90 minutes40 questions – 90 minutes Raw Score = total correct – ¼ * total incorrectRaw Score = total correct – ¼ * total incorrect 1.25 * M.C. Raw Score → possible 50 points1.25 * M.C. Raw Score → possible 50 points

AP ScoringAP Scoring22ndnd Section - Free Response Section - Free Response (90 minutes)(90 minutes)

5 Open-Ended Questions5 Open-Ended Questions 1.875 * Score → possible 7.5 points each 1.875 * Score → possible 7.5 points each 5 questions * 7.5→ possible 37.5 points5 questions * 7.5→ possible 37.5 points

1 Investigative Task1 Investigative Task (reserve 25 min.) (reserve 25 min.) 3.125 * Score → possible 12.5 points 3.125 * Score → possible 12.5 points

Total points possible = 50 Total points possible = 50

AP ScoringAP Scoring

Total Points on Exam: 100Total Points on Exam: 100

For the 2007 AP Exam:For the 2007 AP Exam:

Total PointsTotal Points AP GradeAP Grade

60 – 10060 – 100 5 5

45 – 5945 – 59 4 4

32 – 4432 – 44 3 3

23 – 3123 – 31 2 2

0 – 220 – 22 1 1

General tips for writing General tips for writing free response answersfree response answers

1.Understand that your obligation as a test 1.Understand that your obligation as a test taker is to convince the reader that you taker is to convince the reader that you understand the key concepts in the understand the key concepts in the question. You are evaluated both on the question. You are evaluated both on the correctness of your answers and on your correctness of your answers and on your ability to communicate the methods you ability to communicate the methods you used to reach them. used to reach them.

Adapted from Zack Bigner post to the AP Statistics EDG

Writing FRQ tipsWriting FRQ tips

2.Be aware that “naked” numerical answers 2.Be aware that “naked” numerical answers receive no credit; similarly, single word receive no credit; similarly, single word answers, for example, “yes” or “no,” receive answers, for example, “yes” or “no,” receive no credit without justification. no credit without justification.

3.Calculator syntax will not be sufficient for 3.Calculator syntax will not be sufficient for full credit. full credit.


4.4.Read all the parts of a question Read all the parts of a question and think and think about how they are related about how they are related before you before you begin writing your answerbegin writing your answer. If one part asks . If one part asks you to answer a question based on the you to answer a question based on the result of a previous part that you could not result of a previous part that you could not do, make up an answer to the previous part do, make up an answer to the previous part so that you can continue. Sometimes the so that you can continue. Sometimes the later parts of a question do not depend on later parts of a question do not depend on the parts that come before. Be sure to read the parts that come before. Be sure to read every part of a question so that you don’t every part of a question so that you don’t overlook later parts that you can answer. overlook later parts that you can answer.


5. Answer the question that you are asked. 5. Answer the question that you are asked. Read each question carefully to make Read each question carefully to make sure you really understand what is being sure you really understand what is being asked.asked.

6. When you have answered the question, 6. When you have answered the question, quit writing. Generally you are given more quit writing. Generally you are given more space than you need.space than you need.

7. Answer the question in context. This is 7. Answer the question in context. This is especially important when writing especially important when writing conclusions. conclusions.


8. Use standard symbols and be sure to 8. Use standard symbols and be sure to define any symbols that you make up. Be define any symbols that you make up. Be careful not to confuse symbols for careful not to confuse symbols for population parameters and symbols for population parameters and symbols for sample statistics.sample statistics.

9. Use vocabulary very carefully. Be 9. Use vocabulary very carefully. Be especially careful when you use the words especially careful when you use the words normalnormal and and significant.significant.

10. Avoid using the pronoun “it” unless the 10. Avoid using the pronoun “it” unless the antecedent is clear. You will not get full antecedent is clear. You will not get full credit for a vague answer. credit for a vague answer.


11. Leave sufficient time for the investigative 11. Leave sufficient time for the investigative task. One strategy is to work several of the task. One strategy is to work several of the other free response questions that seem other free response questions that seem easy to you and then work on the easy to you and then work on the investigative task for awhile. If you run out investigative task for awhile. If you run out of time, it would be better to omit one of the of time, it would be better to omit one of the five regular free response questions, since five regular free response questions, since they count less than the Investigative Task. they count less than the Investigative Task.


12. Provide only one answer to a question. 12. Provide only one answer to a question. When students provide two solutions, AP When students provide two solutions, AP Statistics readers will grade both solutions Statistics readers will grade both solutions and record the lower sore. So you will and record the lower sore. So you will waste precious time if you work a problem waste precious time if you work a problem two ways.two ways.

13.If you decide to change an answer, be 13.If you decide to change an answer, be sure to cross out or erase the incorrect sure to cross out or erase the incorrect answer. Often crossing out the answer is answer. Often crossing out the answer is quicker, if you have room for the new quicker, if you have room for the new answer. answer.


14.On both Multiple Choice and Free 14.On both Multiple Choice and Free Response questions, skip questions that Response questions, skip questions that seem hard to you. Come back and work seem hard to you. Come back and work on these questions if time permits. on these questions if time permits.

15.Write neatly and clearly. 15.Write neatly and clearly.

Writing answers to significance test Writing answers to significance test FRQsFRQs

These problems are graded These problems are graded veryvery strictly strictly according to a four-part rubric. Read the according to a four-part rubric. Read the question to determine which statistical test question to determine which statistical test is appropriate. Then be sure to: is appropriate. Then be sure to:

1.State the hypotheses in terms of population 1.State the hypotheses in terms of population parameters, using standard symbols and parameters, using standard symbols and words that communicate the context of the words that communicate the context of the test. test.

Significance Test FRQSignificance Test FRQ

2.Identify the test that you will perform. Then 2.Identify the test that you will perform. Then state the conditions and verify that the state the conditions and verify that the conditions are satisfied. It is not sufficient conditions are satisfied. It is not sufficient to simply state the conditions. You must to simply state the conditions. You must convince the reader that you have checked convince the reader that you have checked the conditions. For example, be sure to the conditions. For example, be sure to show a graph to satisfy a normality show a graph to satisfy a normality assumption for a small sample t-test. assumption for a small sample t-test.


3.Calculate the test statistic and the 3.Calculate the test statistic and the PP-value. -value. Also state degrees of freedom if Also state degrees of freedom if appropriate. You may use your calculator appropriate. You may use your calculator for the computations, but showing the for the computations, but showing the formula and substitutions for your test formula and substitutions for your test statistic may earn you some “holistic” credit statistic may earn you some “holistic” credit when the problem is scored. when the problem is scored.


4. State your conclusion (reject or fail to reject the 4. State your conclusion (reject or fail to reject the null hypothesis) in context and connect it to the null hypothesis) in context and connect it to the PP--value. For example, you can write something like value. For example, you can write something like “since the P-value is less than .05, I will reject the “since the P-value is less than .05, I will reject the null hypothesis and conclude that the mean length null hypothesis and conclude that the mean length of the population of fish of this species is less than of the population of fish of this species is less than 10 inches” or “since the P-value is greater 10 inches” or “since the P-value is greater than .05, I fail to reject the null hypothesis and than .05, I fail to reject the null hypothesis and conclude that the mean length of the population of conclude that the mean length of the population of fish of this species is not significantly less than 10 fish of this species is not significantly less than 10 inches.” inches.”

Writing answers to confidence Writing answers to confidence interval Free Response Questionsinterval Free Response Questions

These problems are graded very strictlyThese problems are graded very strictlyaccording to a four-part rubric. Read theaccording to a four-part rubric. Read thequestion to determine which confidencequestion to determine which confidenceinterval procedure is appropriate. Then beinterval procedure is appropriate. Then besure to: sure to:

1. Identify the confidence interval procedure 1. Identify the confidence interval procedure that you will use. that you will use.

Confidence Interval FRQConfidence Interval FRQ2.State and verify that the conditions are 2.State and verify that the conditions are

satisfied. It is not sufficient to simply state satisfied. It is not sufficient to simply state the conditions. You must convince the the conditions. You must convince the reader that the conditions have been reader that the conditions have been checked and are satisfied. For example, be checked and are satisfied. For example, be sure to show that sure to show that n n >> 10 10 andand nn(1– (1– )) >> 10 10 to satisfy the conditions for a to satisfy the conditions for a zz-confidence -confidence interval for a population proportion. interval for a population proportion.

p̂ p̂

Confidence Interval FRQConfidence Interval FRQ

3.Carry out the computations for the 3.Carry out the computations for the confidence interval. Be sure to state confidence interval. Be sure to state degrees of freedom if appropriate.degrees of freedom if appropriate.

4.Interpret your confidence interval in the 4.Interpret your confidence interval in the context of the problem. context of the problem.

Use your calculator wiselyUse your calculator wisely

Calculators can save you lots of time on both Calculators can save you lots of time on both

Multiple Choice and Free Response questions. Be Multiple Choice and Free Response questions. Be

sure to review the syntax your calculator uses for sure to review the syntax your calculator uses for

Computing summary statistics Computing summary statistics Binomial probability computationsBinomial probability computations Computations associated with normal, t, and Computations associated with normal, t, and χχ22

distributionsdistributions Computing linear regression equations Computing linear regression equations

Calculator UsageCalculator Usage Also, be sure that you know how to create Also, be sure that you know how to create

statistical graphs, including boxplots, statistical graphs, including boxplots, histograms, normal probability plots, scatter histograms, normal probability plots, scatter plots (with and without regression lines), plots (with and without regression lines), and residual plots.and residual plots.

You should also be familiar with the You should also be familiar with the confidence intervals and significance tests confidence intervals and significance tests that your calculator will perform. Entering that your calculator will perform. Entering the two-way table for the two-way table for χχ22 tests may require tests may require matrices, so be sure to review these matrices, so be sure to review these procedures before the AP exam.procedures before the AP exam.

Calculator UsageCalculator Usage

As stated previously, As stated previously, calculator syntax calculator syntax will NOT provide sufficient support for will NOT provide sufficient support for numerical answers.numerical answers. Be sure to give Be sure to give additional support for your answer that additional support for your answer that communicates your understanding of the communicates your understanding of the procedure or computation.procedure or computation.

Reviewing for the examReviewing for the exam

1.Begin a systematic review several weeks 1.Begin a systematic review several weeks before the exam. Your teacher will provide before the exam. Your teacher will provide you with the list of topics covered on the you with the list of topics covered on the exam. exam.

2.As you look over the topics, spend time 2.As you look over the topics, spend time studying topics that you struggled with studying topics that you struggled with during the course or that you have during the course or that you have forgotten. forgotten.

Reviewing for the examReviewing for the exam

3.Practice writing good free response answers. The 3.Practice writing good free response answers. The handouts that you received at prep sessions have handouts that you received at prep sessions have lots of old free response questions, and many lots of old free response questions, and many sample solutions are provided. sample solutions are provided.

4.Write answers to problems and then compare your 4.Write answers to problems and then compare your answer to the model solution. Remember, your answer to the model solution. Remember, your goal is to get maximum credit for what you know. goal is to get maximum credit for what you know. Do not try to cut corners in your answer. The Do not try to cut corners in your answer. The graders read only what you write, not what they graders read only what you write, not what they may think you meant. may think you meant.

Last Minute RemindersLast Minute Reminders

Get a good night’s sleep before the exam.Get a good night’s sleep before the exam. If you are taking the AP Spanish exam the If you are taking the AP Spanish exam the

morning before the AP Statistics exam, be sure morning before the AP Statistics exam, be sure to bring a bag lunch – time between exams will to bring a bag lunch – time between exams will probably be limited.probably be limited.

Make sure your calculator has good batteries. Make sure your calculator has good batteries. Note that you are allowed to bring Note that you are allowed to bring two two calculatorscalculators to the exam. to the exam.

Bring extra pencils.Bring extra pencils. Do not panic! Keep in mind that it usually takes Do not panic! Keep in mind that it usually takes

less than 70 points to get a 5 on the exam.less than 70 points to get a 5 on the exam.

Free Response Question – 2007 # 3Free Response Question – 2007 # 3

FRQ – 2007 # 3FRQ – 2007 # 3 Student ResponseStudent Response Score:4Score:4



Free Response Question – 2007 # 4Free Response Question – 2007 # 4




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AP Statistics Exam Hints