Statistics

1
Statistics

• Spring 2007

2
Introduction

• Dr. Robb T. Koether
• Office Bagby 114
• Office phone [phone]
• Home phone [phone] (before 1100 p.m.)
• Office hours 230-320 MTWR
• Other hours by appointment
• E-mail rkoether_at_hsc.edu
• Web page http//people.hsc.edu/faculty-staff/robb
  k

3
The Course

• The class meets in Bagby 106 at 130 - 220 MTWF.
  
• The text for the course is Interactive
  Statistics, 3rd ed., by Martha Aliaga and Brenda
  Gunderson.
• The web page for this course is at
• http//people.hsc.edu/faculty-staff/robbk/Math121
• Course information is also available through
  Blackboard.

4
Introduction

• Syllabus
• Lectures
• Assignments
• Page xi Interactive Exercises
• Page xvi Graphing Calculator

5
Grading

• There will be
• Weekly quizzes
• Some Excel assignments
• Three tests
• A final exam

6
Grading

• In the final average, these will have the
  following weights

Category Weight
Average of quizzes Excel 30
Average of the tests 50
The final exam 20
7
Homework

• The homework is the most important part of this
  course.
• Learning mathematics requires gaining knowledge
  and understanding, but more importantly doing
  mathematics is a skill.
• You should not expect to acquire a skill by
  listening to a lecturer talk about it. It takes
  practice.
• Do all of the homework every day.

8
Homework

• More importantly, do not put off doing the
  homework until the night before the quiz.
• You will not be able to learn that much material
  in one night.
• Most importantly of all, do not put off doing the
  homework until the day before a test.
• By then it is too late to learn it.

9
Homework

• At the beginning of each class meeting, I will
  spend up to 10 minutes working one or two
  homework problems in detail from previous
  assignments.
• You may request a problem that you would like to
  see worked.
• Of course, outside of class, I will help you with
  as many problems as I can.

10
Quizzes

• Each Tuesday, after going over homework problems,
  there will be a 10-minute quiz.
• The quiz will contain 1 to 3 questions taken from
  the previous week's homework assignments.
• The problems will be copied verbatim from the
  book.

11
Excel Assignments

• From time to time, as appropriate, I will assign
  small projects that will be worked using
  Microsoft Excel.
• You will be allowed and encouraged to work in
  pairs on these assignments.
• These will be graded with the same weight as the
  quizzes.

12
Tests

• The test schedule is as follows

Test Date Coverage
1 Fri, Feb 16 Chapters 1, 2, 3, 4
2 Fri, Mar 23 Chapters 5, 6, 7
3 Fri, Apr 20 Chapters 8, 9, 10, 11
13
The Final Exam

• The final exam will be cumulative.
• It will be given in this classroom at the time
  stated in the exam schedule.
• Everyone must take it.
• It will not be rescheduled.
• Do not schedule a flight home before the exam!
  You will lose your ticket.

14
Attendance

• Attendance will be checked at the beginning of
  each class.
• Two late arrivals will be counted as one absence.
  
• The only valid excuses for missing class are
• An illness which includes a visit to the Health
  Center or a doctor
• An approved college activity
• A true emergency
• Any absence excused by the Dean of Students

15
Attendance

• Sending me an e-mail or leaving me a voice
  message does not excuse you from class.

16
Attendance

• When assigning final grades, attendance will be
  taken into account.

Absences Action
0 2 Grade bonus
3 5 Neutral
6 8 Grade penalty
gt 8 Withdrawal
17
Calculators

• A calculator will be necessary for this course.
• I strongly recommend the TI-83 or the TI-84.

18
The Honor Code

• Quizzes, tests, and the final exam are pledged.
• On Excel assignments you may work with a partner.

19
Classroom Etiquette

• During a lecture, you are free to ask questions.
• It is polite to raise your hand first and wait to
  be called on.
• You should not talk to other students while I am
  talking.
• While working assigned problems in class, you are
  free to talk to other students provided you are
  talking about the assigned problems.

20
Classroom Etiquette

• Do not make leave the room during the class.
• If necessary, use the bathroom before coming to
  class.
• If you are thirsty, get a drink before class.
• Do not sleep in class.
• Do not work on assignments from other classes
  during class.
• Do not read the newspaper during class.

21
The Scientific Method

• Formulate a theory.
• Collect some data.
• Summarize the results.
• Make a decision.

22
The Scientific Method

• Formulate a theory Chapter 1.
• Collect some data.
• Summarize the results.
• Make a decision.

23
The Scientific Method

• Formulate a theory Chapter 1.
• Collect some data Chapters 2 3.
• Summarize the results.
• Make a decision.

24
The Scientific Method

• Formulate a theory Chapter 1.
• Collect some data Chapters 2 3.
• Summarize the results Chapters 4 5.
• Make a decision.

25
The Scientific Method

• Formulate a theory Chapter 1.
• Collect some data Chapters 2 3.
• Summarize the results Chapters 4 5.
• Make a decision Chapters 9 14.

26
The Scientific Method

• Formulate a theory Chapter 1.
• Collect some data Chapters 2 3.
• Summarize the results Chapters 4 5.
• Make a decision Chapters 9 14.
• Theoretical underpinnings Chapters 6 8.

27
Formulate a Theory

• We are wondering whether a particular die is
  fair.
• If it is fair, then the numbers 1, 2, 3, 4, 5,
  and 6 should come up equally often.
• In particular, if we rolled the die 600 times, we
  expect to get each number 100 times.

28
Formulate a Theory

• Or do we?

29
Formulate a Theory

• The theory that the die is fair will be tested by
  posing it as a question with two competing
  answers.
• Question Does the distribution of observed rolls
  match what we would expect to see if the die were
  fair?

30
Formulate a Theory

• The possible answers (yes and no) are stated more
  precisely as two competing hypotheses
• Null hypothesis The die is fair.
• Any deviations from the expected observation are
  due entirely to chance.
• Research hypothesis The die is not fair.
• Any deviations from the expected observations are
  due to the bias in the die.

31
Collect Some Data

• So we roll the die 600 times and get the
  following results.

Number 1 2 3 4 5 6
Expected 100 100 100 100 100 100
Observed 97 97 96 90 102 118
32
Two Possible Explanations

• There is a discrepancy.
• Can it be explained by chance?

33
Summarize the Results

• We use the TI-83 or TI-84, and compute a special
  quantity
• ?2 4.62.

34
Summarize the Results

• Use the TI-83 or TI-84, and compute a special
  quantity
• ?2 4.62.
• If the die really is fair, then theory says that
  we expect this calculation to yield the value 5,
  plus or minus a bit.

35
Make a Decision

• Theory says that if the die is fair, then this
  value should be less than the critical value of
  11.070.
• Since ?2 is less than the critical value, we
  conclude that the null hypothesis is correct
• The die is fair.

36
An Important Question

• Does this procedure prove that the die is fair?

37
An Important Question

• Does this procedure prove that the die is fair?
• We may that it proves it statistically, but it
  does not prove it logically.