Results

Repeated Measures ANOVA

Within Subjects Effects
Cases Sum of Squares df Mean Square F p ω²ₚ
Alcohol 115.860 2 57.930 74.745 < .001 0.682
Residuals 29.451 38 0.775      
Speed 638.035 2 319.017 278.854 < .001 0.903
Residuals 43.473 38 1.144      
Alcohol ✻ Speed 39.879 4 9.970 9.058 < .001 0.243
Residuals 83.648 76 1.101      
Note.  Type III Sum of Squares
Between Subjects Effects
Cases Sum of Squares df Mean Square F p
Residuals 21.217 19 1.117    
Note.  Type III Sum of Squares

Descriptives

Descriptives plots

Post Hoc Tests

Post Hoc Comparisons - Alcohol ✻ Speed - Conditional on Alcohol
Alcohol Mean Difference SE df t pholm
None None(s) Some(s) -3.047 0.305 19 -10.003 < .001
    Much(s) -4.362 0.358 19 -12.188 < .001
  Some(s) Much(s) -1.315 0.255 19 -5.161 < .001
Some None(s) Some(s) -2.818 0.398 19 -7.077 < .001
    Much(s) -4.560 0.390 19 -11.677 < .001
  Some(s) Much(s) -1.743 0.196 19 -8.896 < .001
Much None(s) Some(s) -1.101 0.348 19 -3.166 .005
    Much(s) -4.913 0.351 19 -13.991 < .001
  Some(s) Much(s) -3.811 0.352 19 -10.821 < .001
Note.  P-value adjusted for comparing a family of 3 estimates.
Post Hoc Comparisons - Alcohol ✻ Speed - Conditional on Speed
Speed Mean Difference SE df t pholm
None(s) None Some -0.534 0.313 19 -1.708 .104
    Much -2.367 0.350 19 -6.757 < .001
  Some Much -1.833 0.387 19 -4.737 < .001
Some(s) None Some -0.304 0.247 19 -1.235 .671
    Much -0.421 0.335 19 -1.258 .671
  Some Much -0.117 0.339 19 -0.345 .734
Much(s) None Some -0.732 0.272 19 -2.691 .014
    Much -2.918 0.299 19 -9.748 < .001
  Some Much -2.186 0.267 19 -8.192 < .001
Note.  P-value adjusted for comparing a family of 3 estimates.

Simple Main Effects

Simple main effects are conditional RM ANOVA's: here we do an ANOVA on the effect of Alcohol, for each level of Speed separately. We can see that for some speed, there is no effect of alcohol (which is in line with what we see in the descriptives plot and conditional post hoc tests).

Simple Main Effects - Alcohol
Level of Speed Sum of Squares df Mean Square F p
None(s) 61.652 2 30.826 24.981 < .001
Some(s) 1.894 2 0.947 0.987 .382
Much(s) 92.194 2 46.097 58.894 < .001
Note.  Type III Sum of Squares

Mixed ANOVA

Within Subjects Effects
Cases Sum of Squares df Mean Square F p
Alcohol 115.860 2 57.930 72.376 < .001
Alcohol ✻ Daytime 0.637 2 0.319 0.398 .675
Residuals 28.814 36 0.800    
Speed 638.035 2 319.017 277.016 < .001
Speed ✻ Daytime 2.015 2 1.007 0.875 .426
Residuals 41.458 36 1.152    
Alcohol ✻ Speed 39.879 4 9.970 8.822 < .001
Alcohol ✻ Speed ✻ Daytime 2.279 4 0.570 0.504 .733
Residuals 81.369 72 1.130    
Note.  Type III Sum of Squares
Between Subjects Effects
Cases Sum of Squares df Mean Square F p
Daytime 0.127 1 0.127 0.109 .745
Residuals 21.090 18 1.172    
Note.  Type III Sum of Squares