Introduction to Statistics

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Introduction to Statistics

• UGH!

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Statistics

• Are NOT MATHEMATICS (although they do take
  advantage of some mathematical concepts,
  procedures, notation)
• ARE tools which we use to help us to identify
  understand information contained in data (i.e.
  search for patterns)

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Some Basic Terms

• Statistics can mean either
• Data, or
• Analytic methods results
• The number of variables being analyzed at one
  time is described by
• Univariate (one at a time)
• Bivariate (two at a time)
• Multivariate (three or more)

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Approaches

• Tables
• Frequency distributions (univariate)
• Crosstabulations (bi- and multi- variate)
• Summary statistics

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Building Frequency Distributions

• Identify categories, or
• Create them by collapsing (recoding) variables
  with large numbers of categories
• Determine the number of cases falling into each
  category

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Presenting Frequency Distributions

• See Statistical Tables under Lecture Slides on
  course Web site, and
• Check this

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Crosstabulations Two Or More Variables At Once

• Identify associations
• Examine impact(s) of controls

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Presenting Crosstabulations

• See Statistical Tables under Lecture Slides on
  course Web site, and
• Check this

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Tables Have Some Drawbacks

• Take up space
• May be overly detailed
• So we try to SUMMARIZE variables by using
  statistics

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Summary Statistics

• Using A Single Number To Measure
• Typicality
• Dispersion
• Association

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Presenting Frequency Distributions

• See LeRoy, pgs. 141-144, Tables 8.1 8.2
• Table number
• Title
• Categories category labels
• Frequencies, numbers of cases
• Total number of cases
• Percentages
• Sources, wording, etc

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Presenting Crosstabulations

• See LeRoy, pgs. 165-167, Table 9.5
• Table number
• Title
• Row column labels
• Independent variable on columns
• s calculated in direction of i.v.
• Cell frequencies
• Marginal totals (for i.v.)

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