Lecture 02: Chapter 1

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Lecture 02Chapter 1

• Statistics for Psychology
• David Wallace Croft
• 2005 May 18 Wed

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Quiz 1

• Please mute your mobile phones
• Write your name on a blank piece of paper
• Quiz will begin at 0900
• When done, turn your paper over
• At 0902, I will say, Pens down
• Writing after Pens down is cheating
• Pass your quizzes to your left

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Outline

• Absences
• Calculators
• Research Exposure Credits Requirement
• Textbook Slides
• Emphasis
• Homework

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Absences

• No makeup for daily quizzes
• Please limit missed exams to emergencies
• Early notification of absence is good

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Calculators

• Not allowed for first exam
• Might be allowed for future exams
• Not sure yet

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Research ExposureCredits Requirement

• Detailed Handout
• Required to Complete Course
• Journal Article Option
• textbook footnote, p45
• Catanzaro, D., Taylor, J.C. (1996). The
  scaling of dispersion and correlation A
  comparison of least-squares and absolute
  deviation statistics. British Journal of
  Mathematical and Statistical Psychology, 49,
  171-188.

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Textbook Slides

• Chapter 1 Displaying the Order in a Group of
  Numbers
• http//wps.prenhall.com/hss_aron_statistics_3/0,65
  90,401853-,00.html

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Emphasis

• Boxes on Test
• Frequency Polygon Zeroes
• Direction of Skew
• Median Household Income

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Direction of Skew 1

• A skewed distribution has one side that is long
  and spread out, somewhat like a tail. The side
  with the fewer scores (the side that looks more
  like a tail) is considered the direction of the
  skew.
• -- textbook, p20

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Direction of Skew 2

• In probability theory and statistics, skewness
  is a measure of the asymmetry of the probability
  distribution of a real-valued random variable.
  Roughly speaking, a distribution has positive
  skew (right-skewed) if the higher tail is longer
  and negative skew (left-skewed) if the lower tail
  is longer getting these the wrong way round is a
  common error.
• -- Skewness, Wikipedia

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Median Household Income

• floor effect
• skewed to the right
• mean higher than median
• mnemonic

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Homework

• Optional
• Do not turn in
• Will help you on the exams
• Answers to Set I problems in back of book
• I have answers to Set II problems
• Will help you on the exams

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Next Class

• Friday
• Chapter 2
• Mean, Variance, Standard Dev, Z Scores
• Read Chapter 2 Before Class
• Pre-Lecture Quiz
• Starts at 0900
• Ends at 0902
• Exam 1 on Monday

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Questions

• Questions for Class?
• Post to e-mail list unless personal
• http//egroups.com/group/utd-statistics