Results

ANOVA

ANOVA - accidents
Cases Sum of Squares df Mean Square F p ω²ₚ
alcohol 364.146 2 182.073 469.271 < .001 0.839
speed 128.164 2 64.082 165.164 < .001 0.646
alcohol ✻ speed 1.911 4 0.478 1.231 0.299 0.005
Residuals 66.346 171 0.388  
Note.  Type III Sum of Squares

Descriptives

Descriptives plots

Assumption Checks

Q-Q Plot

Post Hoc Tests

Standard (LSD)

Post Hoc Comparisons - alcohol ✻ speed - Conditional on alcohol
alcohol Mean Difference SE t ptukey
none none some -0.839 0.197 -4.257 < .001
    much -1.782 0.197 -9.047 < .001
  some much -0.944 0.197 -4.790 < .001
some none some -1.319 0.197 -6.696 < .001
    much -2.136 0.197 -10.841 < .001
  some much -0.817 0.197 -4.145 < .001
much none some -1.216 0.197 -6.171 < .001
    much -2.275 0.197 -11.550 < .001
  some much -1.060 0.197 -5.379 < .001
Note.  P-value adjusted for comparing a family of 3
Post Hoc Comparisons - alcohol ✻ speed - Conditional on speed
speed Mean Difference SE t ptukey
none none some -1.338 0.197 -6.790 < .001
    much -3.191 0.197 -16.200 < .001
  some much -1.854 0.197 -9.410 < .001
some none some -1.818 0.197 -9.230 < .001
    much -3.568 0.197 -18.114 < .001
  some much -1.750 0.197 -8.884 < .001
much none some -1.691 0.197 -8.585 < .001
    much -3.684 0.197 -18.703 < .001
  some much -1.993 0.197 -10.118 < .001
Note.  P-value adjusted for comparing a family of 3
Post Hoc Comparisons - alcohol
Mean Difference SE t ptukey
none some -1.616 0.114 -14.206 < .001
  much -3.481 0.114 -30.609 < .001
some much -1.866 0.114 -16.404 < .001
Note.  P-value adjusted for comparing a family of 3
Note.  Results are averaged over the levels of: speed
Post Hoc Comparisons - speed
Mean Difference SE t ptukey
none some -1.124 0.114 -9.887 < .001
  much -2.064 0.114 -18.151 < .001
some much -0.940 0.114 -8.264 < .001
Note.  P-value adjusted for comparing a family of 3
Note.  Results are averaged over the levels of: alcohol