Table 1. Average correlations and stiffnesses with standard deviations for each stiffness calculation method Constant Stiffness High-low Stiffnessx r Stiffness (kN·m) r High Stiffness (kN·m) Low Stiffness (kN·m) Average (SD) .948 (.026) 28.7 (5.0) .994(.004) 75.3 (15.2) 31.2 (4.1)