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Microsoft PowerPoint - Unit 00 - Introduction to Statistics by qlc15660


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									                                                                                                        Teaching Staff
            Welcome to Stat S-100
     Introduction to Quantitative Methods                                           • My office: Science Center, Room SC-602
                                                                                      • Office Hours:
                                                                                          • Mon and Wed: 5-6pm
                            Kevin Rader                                                   • Also by appointment (via email)
                        Preceptor in Statistics
             Statistics Department, Harvard University                              • Phone numbers:
                                                      • Statistics Department: (617) 495-5496
                                                                                       • Room SC-602: (617) 496-4879

If you want to inspire confidence, give plenty of statistics. It does not matter    • Email: (preferred)
that they should be accurate, or even intelligible, as long as there is enough of
them. Lewis Carroll

                    Teaching Staff                                                                      Teaching Staff

• Co-Lecturer: Dr. Dave Harrington                                                      • Head Teaching Assistant (TA): Andy Vesper

• Cambridge office: Science Center, Room 300-A                                          • Other Teaching Assistants:
   • Office Hours: By appointment and 4-5pm on:                                            • Michelle Bai
                                                                                           • Valeria Espinosa
      • June 24, 29; July 1, 8, 13
                                                                                           • Jon Hennessy
                                                                                           • Joey Kelly
• Email:
                                                                                        • Teaching assistants will be teaching sections, holding office
                                                                                          hours, answering questions via email, and grading

                        Course Website                                                                       Lecture Notes
                                                                                    • Paper copies will NOT be handed out at the beginning of
  • Course website:                                                lecture after this week (you will receive copies on Wed).
  • There you will find:                                                            •    They’re organized in Units: which follow chapters in the
     • Syllabus                                                                          textbook (though will diverge a bit at end of semester)
     • Administrative Announcements                                                 •    Lecture notes will be posted by Friday for the next week’s
     • Lecture Notes                                                                     lectures
     • Stata Tutorial                                                               •    Notes quite concise – you are encouraged to add your own
     • Assigned Homeworks                                                                annotations and develop your own notes
        • HW #1 is now listed: Due Mon, June 29th                                   •    Occasionally mistakes appear in lecture notes; corrected
     • Other Study Material (old exams, web links, etc...)                               versions will be posted after class
                        Class Meetings
• Lectures:                                                                                                     Textbook
   • Mon & Wed 6:30–9:30pm, Science Center A
   • 10-minute break at halftime; great time to ask questions
                                                                             • Moore, McCabe, and Craig. (2009). Introduction to the
• Sections
                                                                                  Practice of Statistics, (6th edition). W.H. Freeman.
   • Optional (but strongly recommended) weekly section to discuss
      homework, do extra problems, and review difficult concepts.                  • website -
   • This week’s sections, tentatively (locations TBD):                            • (5th edition will work fine too)
        • Wed 5:30-6:30pm (in Lecture Hall A)                                •    About half of the assigned homework problems will be
        • Thurs 5:30-6:30pm                                                       assigned from the text, so it’s a good idea to have a copy.
        • Thurs 6:30-7:30pm                                                       Plus, you can use it during exams.
• Permanent Schedule will be different according to need. Look for           •    It’s a great reference for more details on what is seen in the
  announcement on the website (office hours will be listed there too).            lectures. Very straightforward explanations.

        Computing and Calculations                                                                                 Exams
  • For all exams (and some homework), you will need a
    calculator with log, exponential, square-root functions.                 • Mon, July 13th: Midterm: 6:30-8pm

  • Statistical Computing Package: Stata SE                                  • Mon, Aug 3rd: Final Exam: 6:45-9:45pm
     • Can be downloaded from:
     • Tutorial on website:                                                  • They are open-book and open-notes

      • This week’s section (and HW) will be an introduction
        to the software
                                                                             • Locations TBD

                              Homeworks                                                                   Course Grading
 • Posted to course website on Mondays:                                                        Component                                            Weight

 • Must be handed into your TA (or Andy or Kevin) on Due                                      Problem Sets                                            35%
    Date:                                                                                        Midterm                                              25%
    Assignment       Due Date
    HW 1             Mon, June 29th                                                            Final Exam                                             40%
    HW 2             Mon, July 6th
    HW 3             Fri, July 10th by 5pm                                                         Total                                             100%
    HW 4             Mon, July 20th                                         Final course letter grades are not assigned according to a fixed percentages of A's, B's etc
                                                                               (i.e., the course is not `curved'). Letter grades are assigned to the old-fashioned
    HW 5             Mon, July276th
                                                                               boundaries of A- to A: 90 - 100 final score; B- to B+: 80 - 90, etc. Slight adjustments
    HW 6             Fri, July 29th by 5pm                                     may be made on the boundaries of letter grades.
 • Late homeworks will be accepted up to start of following                 Problem sets assigned each Monday (posted on the course web site), 6 in total. Late problem
    class. These will incur a 20% deduction for being late.                    sets well be accepted the following class day with a 20% deduction (max of 80%). No
                                                                               Problem Set scores will be dropped.
                   What is statistics?                                            Proving Points with Statistics
                (and why is it so cool?)
 • The study of the collection, organization, analysis, and
   interpretation of data
 • Why bother? Principles provide a framework for
    • data collection
    • design of experiments and observational studies
    • drawing inferences about populations as a whole and of
       future events

 • Short story: Statistics is the science of using data to prove
   a point (hopefully forming a correct conclusion).

           Other questions that could be
              addressed statistically                                                                                            Gallup Poll:
                                                                                                                                 Obama’s Job
 • How should I invest my savings? Does this change in a bear
 • What improvements should I make to my house before selling it?                                          Gallup Poll: Obama Job Approval, June 16-18, 2009
 Health                                                                                              60

 • Does a smoking ban in bars lower the rate of lung cancer?                                         50

 • Does talking on a cell phone lead to higher risk of a car accident?                               40


 • Is David Ortiz truly a clutch hitter? Is Alex Rodriguez anti-clutch?                              20

 • Is offense or defense more important to winning in the NFL?

                                                                                                          Approve   Disapprove     Other       Neither    No Opinion

     Gallup Poll on Obama’s Job Performance
• “Thirty-three percent of Americans now disapprove of the job
  Obama is doing as president, just one point shy of his record-high
  34% disapproval score from early June.”                                   •   How representative is this of general attitudes?
                                                                                     What might ensure this poll is representative?
• “Results are based on telephone interviews with 1,504 national            •   Would this poll turn out exactly the same way every time, even
  adults, aged 18 and older, conducted June 16-18, 2009, as part of             if different participants were chosen?
  Gallup Poll Daily tracking. For results based on the total sample of
  national adults, one can say with 95% confidence that the maximum         •   What does the Gallup organization mean by the phrase: “the
  margin of sampling error is ±3 percentage points.                             maximum margin of sampling error is ±3 percentage points “
  Interviews are conducted with respondents on land-line telephones         •   We will examine these and other related questions during the
  (for respondents with a land-line telephone) and cellular phones (for         semester
  respondents who are cell-phone only).
  In addition to sampling error, question wording and practical
  difficulties in conducting surveys can introduce error or bias into the
  findings of public opinion polls.”
                                                                                            Final Exam vs Midterm Average

                                                                                                                                                        Confidence Intervals for

                      Another Example

                                                                     Final Exam
•   Final exam scores in Stat 100

    • Next slide shows a plots of average of midterm scores                       40             60
                                                                                                      Midterm A verage
                                                                                                                          80             100

        (horizontal axis) vs final exam score (vertical axis) for                                95% CI
                                                                                                                         Fitted values

        Spring 2005.                                                                                                                                          Final Exam vs Midterm Average

    • The two plots on the next slide use identical data, but have

        different interpretation.

                                                                                                                                          Final Exam
    • No need to take notes, just listen. We will cover this in

        detail later in the course

                                                                                       Prediction Intervals for new                                    40          60                       80             100
                                                                                                                                                                        Midterm A verage
                                                                                       observations                                                                95% CI                  Fitted values

    3 Major Overarching Topics in the Course

1) Describing Data
    - Graphically
    - Numerically

2) Gathering Data
    - Experimental Design and Randomization
    - Observational Data and Random Sampling
    - Randomness and Probability Models

3) Inference
    - showing statistical significance and p-values
    - estimation (confidence intervals) and testing hypothesis

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