Results

ANOVA

ANOVA - injury
95% CI for ω²ₚ
Cases Sum of Squares df Mean Square F p ω²ₚ Lower Upper
athlete 99.008 1 99.008 64.822 < .001 0.347 0.213 0.467
stretch 16.875 1 16.875 11.048 0.001 0.077 0.010 0.186
switch 85.008 1 85.008 55.656 < .001 0.313 0.180 0.436
athlete ✻ stretch 1.875 1 1.875 1.228 0.270 0.002 0.000 0.048
athlete ✻ switch 69.008 1 69.008 45.181 < .001 0.269 0.140 0.394
stretch ✻ switch 21.675 1 21.675 14.191 < .001 0.099 0.019 0.214
athlete ✻ stretch ✻ switch 9.075 1 9.075 5.942 0.016 0.040 0.000 0.132
Residuals 171.067 112 1.527  
Note.  Type III Sum of Squares

Descriptives

There was a significant athlete by stretch by switch interaction *F*(1, 112) = 5.94, *p* < .05,  = 0.04. What this means is that the effect of stretching and playing on the switch on injury score was different for athletes than it was for non-athletes. In the presence of this significant interaction it makes no sense to interpret the main effects. @fig-13_8f shows this three-way effect and includes the significance of the simple effects analysis. Using this information, it seems that for athletes, stretching and playing on the switch has very little effect: their injury scores were low regardless of whether they played on the switch, watched other people playing, stretched or did not stretch. However, for the non-athletes, watching other people play on the switch compared to playing it themselves significantly decreased injuries both when they stretched and did not stretch. Based on the means it looks as though this difference is a little smaller after stretching than not (although we don't have a direct test of this).


As you can see below, a three-way interaction effect implies that a two-way interaction is influenced by a third variable. You can shuffle around the variables and the boxes they are assigned to, to get a clear idea of how the three-way interaction is manifested in the data.

Descriptives plots

athlete: Athlete
athlete: Non-athlete

Simple Main Effects

Simple Main Effects - stretch
Level of athlete Level of switch Sum of Squares df Mean Square F p
Athlete Playing switch 4.800 1 4.800 3.143 0.079
  Watching switch 0.300 1 0.300 0.196 0.658
Non-athlete Playing switch 43.200 1 43.200 28.284 < .001
  Watching switch 1.200 1 1.200 0.786 0.377