CONTROLLED COMPARISONS

1
CONTROLLED COMPARISONS
2
READING

• Pollock, SPSS Companion, chs. 4-5

3
Testing Hypotheses

• Experimental Designs
• The True Experiment pre-measurement, treatment,
  post-measurement for test and control groups
• The Natural Experiment external or ascriptive
  factors (nature) define test or control groups
• Controlled Comparisons
• How else? and holding rival causes constant
• Example Opinions on Gun Control

4
Support for Handgun Control Comparing Percentages
5

• Support for Handgun Control Within Groups
• Gender not Partisanship
• ______ in Favor_______
• Gender Dems Repubs
• Female 60 60
• Male 45 45
• Partisanship not Gender
• _______ in Favor_______
• Gender Dems Repubs
• Female 60 45
• Male 60 45

6

• C. Partisanship and Gender
• ________ in Favor________
• Gender Dems Repubs
• Female 65 55
• Male 40 30

7
RETHINKING GUN CONTROL
__Democrats__ __Republicans__ Female
Male Female Male For 70
50 50 30 Agst 30 50
50 70
8

• The Analytical Challenge(s)
• Establishing cause-and-effect
• Considering unobserved (lurking) variables
• the What else? question
• Assessing roles of other X variables
• Inventing alternative explanations for any
• observed relationship (how might we interpret
• a positive relationship between poverty and
• radicalism?)

9

• Looking Ahead and Beyond.
• What if all bivariate relationships support the
• the separate hypotheses? What then?
• Check relationships among the independent
  variables
• Are they measuring different things? Or the
  same?
• Can we identify the relationship between Y and,
  say, X1,
• while controlling for the effects of X2 and X3?