Presenting the Results of a Contingency Table Analysis

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					Presenting the Results of a
Contingency Table Analysis
      Verdict x Defendant Physical
             Attractiveness
• Mock jurors were significantly more likely to
  find the defendant guilty when he was
  unattractive (75.7%) than when he was
  attractive (65.0%), 2(1, N = 145) = 6.229, p =
  .013,  = .207, odds ratio = 2.45, 95% CI [1.20,
  4.99].
• Please note that with significant results one
  should emphasize the direction of effect.
        Nonsignificant Results
• One should NOT mention direction of effect,
  unless having tested directional hypotheses.
           Direction x Device
• People were significantly more likely to take
  the stairs when going down (24.3%) than
  when going up (6.1%), 2(1, N = 3,217) =
  217.22, p < .001,  = .26, odds ratio = 4.90,
  95% CI [3.91, 6.13].
• SPSS gave me an odds ratio of .204 and a CI of
  [.163, .256]. I inverted these numbers to get
  ratios greater than one.
Figure 1. Device x Weight
   18
   16
   14
   12              Obese
   10
                   Overweight
    8
    6              Normal
    4
    2
    0
        % Stairs
• Choice of device was significantly associated
  with weight of patron, 2(2, N = 3,217) =
  11.752, p = .003,  = .06. As shown in Table 1,
  obese individuals used the stairs considerably
  less often than did others.
         Pairwise Comparisons
• Use of the stairs did not differ significantly
  between overweight and normal individuals,
  2(1, N = 2,907) = 1.034, p = .31, ,  = .02,
  odds ratio = 1.12, 95% CI [0.90, 1.38].
• Individuals of normal weight used the stairs
  significantly more often than did obese
  individuals, 2(1, N = 2,142) = 9.062, p = .003, ,
   = .065, odds ratio = 1.94, 95% CI [1.25, 3.00].
• SPSS will mess up if you use a dichotomous
  predictor that is coded with numbers other than
  consecutive integers, such as Weight = 1 (obese)
  and 3 (normal). If you declare Weight to be
  categorical, SPSS works fine.
• Overweight individuals used the stairs
  significantly more often than did obese
  individuals, 2(1, N = 1,385) = 11.815, p = .001, 
  = .092, odds ratio = 2.16, 95% CI [1.38, 3.38].

				
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posted:2/6/2013
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