Divergence between JASP and SPSS ouptuts when computing polynomial contrasts for within-sjts designs
I am trying to reproduce David Howell's SPSS analysis of the aiport dataset (attached) in JASP. Dave's analysis is available at https://www.uvm.edu/~dhowell/StatPages/More_Stuff/RepMeasMultComp/RepMeasMultComp.html. When performing the polynomial contrast analysis of the effect of time on stress level (condition near aiport only), SPSS returns F(1, 99) = 1.721 p = .193 for the cubic trend while JASP returns t = 1.261 p = .208:
Obviously the t statistic returned by JASP is not equal to the square root of F returned by SPSS. Could you please clarify why?