Political Science 30 Political Inquir

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Political Science 30Political Inquiry

• Sections meet in Solis 105 this week.

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Measurement II. Quantifying and Describing
Variables

• Four Levels of Precision
• Measures of Central Tendency
• Mode
• Median
• Mean
• Measures of Dispersion
• Variance, Standard Deviation

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Four Levels of Precision For Measuring Variables
(Pollock, p.28)

• Nominal Measure You can put cases into a
  category, but cannot specify an order or
  relationship between the categories.
• Example The variable religion can take on
  values such as Catholic, Protestant, Mormon,
  Jewish, etc.

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Four Levels of Precision For Measuring Variables
(Pollock, p.28)

• Ordinal Measure You can put cases into different
  categories, and order the categories.
• Example The variable strength of religious
  belief can take on values such as devoutly
  religious, fairly religious, slightly religious,
  not religious.

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Four Levels of Precision For Measuring Variables
(Pollock, 28-29)

• Interval Measure Not only can you order the
  categories of the variable, you can specify the
  difference between any two categories.
• Example. The variable temperature on the
  Fahrenheit scale can take on values such as 32
  degrees, 74 degrees, 116 degrees.

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Four Levels of Precision For Measuring Variables

• Ratio Measure You can order categories, specify
  the difference between two categories, and the
  value of zero on the variable represents the
  absence of the variable.
• Example. The variable annual income can take
  on the values of 0, 98,000, or 694,294,129.

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Measures of Central Tendency(Pollock, Ch. 2)

• Kobe Bryant 24.8 million
• Pau Gasl 17.8 million
• Andrew Bynum 13.8 million
• Lamar Odom 8.2 million
• Ron Artest 6.3 million
• Luke Walton 5.3 million
• Steve Blake 4.0 million

• Derek Fisher 3.7 million
• Shannon Brown 2.2 million
• Matt Barnes 1.8 million
• Joe Smith 1.4 million
• Theo Ratliff 1.4 million
• Devin Ebanks 0.5 million
• Derek Caracter 0.5 million

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Measures of Central Tendency(Pollock, Ch. 2)

• Mode The most frequently occurring value.
• 1.4 million and 0.5 million
• Median The midpoint of the distribution of
  cases.
• 1. Arrange cases in order
• 2. If the number of cases is odd, median is the
  value taken on by the case in the center of the
  list.
• 3. If the number of cases is even, median is the
  average of the two center values. 3.85 million

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Measures of Central Tendency

• Mean is the arithmetic average of the values that
  all the cases take on. 6.6 million.
• Add up all the values
• Divide this sum by the number of cases, N.

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Measures of Dispersion(Pollock, p.119-124)

• The variance is a measure of how spread out cases
  are, calculated by
• Compute the distance from each case to the mean,
  then square that distance.
• Find the sum of these squared distances, then
  divide it by N-1. 53.8 million.

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Measures of Dispersion(Pollock, pp. 119-124)

• The standard deviation is the square root of the
  variance, 7.3 million.