Data analysis: frequencies

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Data analysis frequencies
GAP Toolkit 5
Training in basic drug abuse data
management and analysis
Training session 8
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Objectives

• Introduce univariate, descriptive statistics as
  the first step in a process of data analysis,
  starting from exploration and moving towards more
  sophisticated techniques
• Distinguish between frequencies and relative
  frequencies
• Introduce frequency and probability distributions
  as data models

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Descriptive Statistics

• Univariate
• Categorical data
• Continuous data

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SPSS Descriptive Statistics

• Analyse/Descriptive Statistics/Frequencies
• Analyse/Descriptive Statistics/Explore
• Analyse/Descriptive Statistics/Descriptives

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Frequency vs relative frequency

• The frequency of any value of a variable is the
  number of times that value occurs in the data
  that is, a frequency is a count. The relative
  frequency of any value is the proportion or
  fraction or percent of all observations that have
  that value.
• (D. S. Moore, Statistics Concepts and
  Controversies, 5th ed. (New York, W. H. Freeman
  Press, 2000)).

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Frequency distribution/probability distribution

• Frequency distribution all possible values of
  the variable and their associated counts
• Probability distribution all possible values of
  the variable and their associated probabilities
  (relative frequencies)

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Percentages

• Let
• f1 the number of cases in category 1
• n the total number of cases
• The percentage of cases in category 1

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Exercise frequency of referral

• Construct a frequency table for referral source
  in the file main.sav

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Referral
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Frequencies Format button
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Referral
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Frequencies Charts button
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(No Transcript)
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Frequencies Statistics button
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Statistics
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Frequencies syntax

• FREQUENCIES
• VARIABLESrefsourc
• /FORMATDFREQ
• /STATISTICSMODE
• /BARCHART PERCENT
• /ORDERANALYSIS.

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Exercise frequencies

• Generate a frequency table and bar chart for each
  of the following variables and comment
• Race
• Education
• Employment
• Save the output and the syntax file

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Frequency Race
Race
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Frequency Education
Education
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Frequency Employment
Employment
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Summary

• Frequencies and relative frequencies
• Frequency distributions and probability
  distributions
• Format/ordering
• Bar charts
• Statistics/mode