Different Kinds of Relationships

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Different Kinds of Relationships

• Additive
• Spurious
• Interactive

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Additive

• Parallel Lines
• Means difference in percentage favoring gun ban
  does not depend on gender

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Additive
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Spurious

• Given two independent variables, one of the
  independent variables affects both the other
  independent variable as well as the dependent
  variable

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Example

• Gender affects both partisanship and attitudes
  toward gun ban
  
• Women tend to be democrats and also tend to favor
  banning guns
  
• If only estimate the relationship between
  partisanship and attitudes toward banning guns
  without controlling for gender (that is, without
  holding gender constant), it will appear that
  more democrats want to ban guns that republicans
  even though there is no relationship between
  partisanship and attitudes toward banning guns

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Spurious
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Spurious
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Interactive

• Nonparallel lines
• Difference in the percentage favoring a gun ban
  is different for men and women

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Interactive
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Cross-Tab Table One Independent Variable
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Cross-Tabs Adding an Independent Variable
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Adding another independent variable cont
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Mean Comparison One Indep. Variable
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Mean Comparison Adding an Indep. Variable