curvature versus slope
  n = 628762 
  X=0, Y = 37.49 +/- 26.12 
  Weighted least-squares fit:  Y = 67.3 + 1.643 X  + -0.01723 X**2 

slope versus dZ, curvature < 5
  n = 17136 

  Weighted least-squares fit:  Y = 167.1 + -1.926 X  + 0.01381 X**2 
     at X = 100, Y = 112.6 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 66039 

  Weighted least-squares fit:  Y = 164.2 + -1.614 X  + 0.01215 X**2 

curvature versus dZ, slope < 10
  n = 4620 
  X=0, Y = 154.73 +/- 85.77 
  Weighted least-squares fit:  Y = 153.4 + 0.666 X  + -0.63484 X**2 


Number of samples 631579
Max dz = 900
Mean dz = 132
RMS dz = 161.746715577
100cm = 40.9126965906 percentile value of dz