What is Statistics

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• What is Statistics?

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• Statistics is a collection of procedures and
  principles for gathering data and analyzing
  information in order to help people make
  decisions when faced with uncertainty.

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Variables

• Individuals are the objects described by a set of
  data.
• A variable is any characteristic of an
  individual.

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individuals
College student
dogs
DOB, gender, major, gpa
Breed, height, color
variables
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• Why? Purpose
• Who? How many individuals
• What? Defined variables and unit of measure

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Data are used to make a judgment about a
situation

• What question needs to be answered?
• How should we collect data how much?
• How can we summarize the data?
• What decisions or generalizations can be made in
  regards to the question based on the data
  collected?

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Data--Types of Variables
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Distribution

• Distribution of a variable tells us what values
  it takes and how often it takes these values
• Form groups of 3, in your group record hair
  color, eye color, age, and etc.
• We will make an excel chart with your data.

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Exploratory Data Analysis

• Using statistical tools and ideas in order to
  describe their main features.
• 1. examine each variable by itself, then its
  relationship
• 2. start with a graph, then add numeric
  summeries.

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Graphs for categorical variables

• Bar graphs, does not need all categories
• Pie Charts, need all categories.

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Summarizing Dataw/ Bar graph of Categorical Data
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Summarizing Data with Pie Chart for Categorical
Data
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Using the TI-8X

• Or How I Stopped Worrying and Love AP Statistics

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Measuring the Speed of Light

• A. A. Michelson and Simon Newcomb in 1882
• Moore pgs 7-8
• Use your calculator.
• Instrument is the device doing the measurement

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Rate vs. Count

• Rate at which something occurs
• Count number of occurences
• Pg 9, Moore. Example 1.3

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Variation

• The pattern of variation of a variableis called
  its distribution.
• Newcomb used the idea of distribution when
  constructing his light experiment.

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Stemplots (Stem and Leaf Plot)

• Gives shape of distribution while including the
  actual numerical values
• 1) make stem from number except for last digit
• 2) draw line
• 3) put final digit

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Stemplot for Quantitative Data

• Ages of Death of U.S. First Ladies
• 3 4, 6
• 4 3
• 5 2, 4, 5, 7, 8
• 6 0, 0, 1, 2, 4, 4, 4, 5, 6, 9
• 7 0, 1, 3, 4, 6, 7, 8, 8
• 8 1, 1, 2, 3, 3, 6, 7, 8, 9, 9
• 9 7

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Split Stemplot

• 1 7
• 1 8, 9, 9, 9, 9, 9
• 2 0, 0, 0, 0, 1, 1, 1, 1, 1, 1
• 2 2, 2, 2, 3, 3
• 2 4, 5
• 2
• 2 8
• 3 0, 1

Stem is split for every 2 leaves
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Back-to-back Stemplot

• Babe Ruth Roger Maris
• 0 8
• 1 3, 4, 6
• 5, 2 2 3, 6, 8
• 5, 4 3 3, 9
• 9, 7, 6, 6, 6, 1, 1 4
• 9, 4, 4 5
• 0 6 1

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Rounding for Stemplots

• Over the next couple of days, bring back any
  receipts you may have acquired.
• Remove any identifying card number, trust me
• We will do a rounded stemplot with them to see
  our spending habits as a society.

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Examining Distributions

• What does it mean?
• In any graph of data, look for the overall
  pattern and for striking deviations from that
  pattern.
• You can describe the overall pattern of a
  distribution by its shape, center, and spread.

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• An outlier is an individual value that falls
  outside the overall pattern.
• For now, let center be the midpoint and spread
  mean the range between the smallest and largest
  value.
• A peak in the data is called a mode, if there is
  only one peek then it is called unimodal.
• Symetric means all values smaller and larger to
  the mode mirror each other.

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Skewed

• Skewed right means that the right tail is longer
• Skewed left means that the left tail is longer