curvature versus slope
  n = 860683 
  X=0, Y = 56.54 +/- 33.10 
  Weighted least-squares fit:  Y = 68.0 + 1.534 X  + -0.01533 X**2 

slope versus dZ, curvature < 5
  n = 53043 

  Weighted least-squares fit:  Y = 18.6 + -0.110 X  + 0.00081 X**2 
     at X = 100, Y = 15.7 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 113342 

  Weighted least-squares fit:  Y = 19.0 + -0.084 X  + 0.00119 X**2 

curvature versus dZ, slope < 10
  n = 18457 
  X=0, Y = 16.99 +/- 8.49 
  Weighted least-squares fit:  Y = 17.7 + 0.514 X  + -0.05622 X**2 


Number of samples 868058
Max dz = 900
Mean dz = 48
RMS dz = 80.4425260668
100cm = 87.7924055766 percentile value of dz