curvature versus slope
  n = 571272 
  X=0, Y = 38.59 +/- 16.91 
  Weighted least-squares fit:  Y = 53.7 + 2.267 X  + -0.02593 X**2 

slope versus dZ, curvature < 5
  n = 186040 

  Weighted least-squares fit:  Y = 90.6 + 0.826 X  + -0.00846 X**2 
     at X = 100, Y = 88.6 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 309327 

  Weighted least-squares fit:  Y = 94.9 + 0.560 X  + -0.00622 X**2 

curvature versus dZ, slope < 10
  n = 5888 
  X=0, Y = 107.12 +/- 55.01 
  Weighted least-squares fit:  Y = 110.3 + -2.172 X  + 0.04240 X**2 


Number of samples 573066
Max dz = 900
Mean dz = 90
RMS dz = 110.516967023
100cm = 61.6443830205 percentile value of dz