LIS 570

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LIS 570

• Summarising and presenting data - Univariate
  analysis continued
• Bivariate analysis

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Selecting analysis and statistical techniques
De Vaus p133
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Methods of analysis (De Vaus, 134)
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Summary

• Inferential statistics for univariate analysis
• Bivariate analysis
• crosstabulation
• the character of relationships - strength,
  direction, nature
• correlation

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Inferential statistics - univariate analysis

• Interval estimates - interval variables
• estimating how accurate the sample mean is
• based on random sampling and probability theory
• Standard error of the mean (Sm)
• Sm s
• ?N

Standard deviation
Total number in the sample
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Standard Error

• Probability theory
• for 95 of samples, the population mean will be
  within or - two standard error units of the
  sample mean
• this range is called the confidence interval
• standard error is a function of sample size
• to reduce the confidence interval, increase the
  sample size

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Inference for non-interval variables

• For nominal and ordinal data
• Variable must have only two categories
• may have to combine categories to achieve this
• SB PQ
• N

P the in one category of the variable Q the
in the other category of the variable
Total number in the sample
Standard error for binominal distribution