SPSS, Counting Responses and Descriptive Statistics

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SPSS, Counting Responses and Descriptive
Statistics

• EDLD 6333
• Introduction to Statistical Reasoning

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SPSS Windows

• Data Editor Window (Data View)
• Columns are variables
• Rows are cases
• Variable View
• Viewer Window
• Outline Pane
• Display Pane
• Editor Window Change properties of tables and
  graphs

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Counting Responses

• Use the frequencies procedure to summarize data
• To get a frequency table
• Analyze?DescriptiveStatistics?Frequencies
• GSSNET.SAV Variable descriptions in text

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Data Set in Variable View
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Frequency Table Dialog Box
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Frequency Table Output
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Percentages

• Needed to make comparisons
• Percent (cases/total100)
• Valid Percent Does not count missing values
• Sometimes, the percent is better
• Cumulative Percent Needs to be an order to the
  responses

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To Organize by Counts
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To Create Pie Charts
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To Create Bar Charts
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When Frequency Tables Are Not Enough

• Frequency Tables, Pie charts and Bar charts will
  not work with a continuous numeric variable such
  as age.
• In stead, each bar can represent a range, rather
  than a distinct value.
• The label on the horizontal axis is the midpoint
  of the range.

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Histogram
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Terms and Concepts

• Symmetric/Asymmetric
• Mode occurs most often
• Use with any type of variable
• Median middle value
• Can only use if the categories have order
• Mean arithmetic average
• Percentiles
• Ask for Quartiles

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Quartiles
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Homework p. 73, 20
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Homework p. 73, 20
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Descriptive Statistics

• Scales of Measurement
• Nominal Scale
• Ordinal Scale
• Interval Scale
• Ratio Scale
• (Dichotomous variables act as interval)

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Descriptive Statistics

• Measures of Central Tendency (p. 78)
• Mean
• Median
• Mode
• Measures of Variability (p. 85)
• Range and Interquartile Range
• Variance and Standard Deviation
• Coefficient of Variation (as of mean)

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Mean, Median, and Mode
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Variance
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Variance and Standard Dev.

• The larger the variance, the more the values are
  spread out.
• Calculation p. 86
• Square Root of s2 SD
• Standard Deviation, in same units as the original
  data.

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Coefficient of Variation

• Represents the SD as a percentage of the mean
  value.
• Can compare over variables.

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Standard Scores

• Called a z Score Using the mean and SD to
  position a score
• Z value mean/SD
• Standard score of 0 mean
• Standard score of 1, -1
• Most values fall within or 2 SDs

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Saving z Scores
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Homework Assignment

• Check the website