curvature versus slope
  n = 5507801 
  X=0, Y = 28.86 +/- 17.12 
  Weighted least-squares fit:  Y = 54.1 + 2.474 X  + -0.02601 X**2 

slope versus dZ, curvature < 5
  n = 54832 

  Weighted least-squares fit:  Y = 23.4 + -0.007 X  + -0.00001 X**2 
     at X = 100, Y = 22.6 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 236649 

  Weighted least-squares fit:  Y = 21.8 + 0.211 X  + -0.00024 X**2 

curvature versus dZ, slope < 10
  n = 36670 
  X=0, Y = 16.31 +/- 10.88 
  Weighted least-squares fit:  Y = 19.5 + 3.779 X  + -0.41669 X**2 


Number of samples 5531605
Max dz = 700
Mean dz = 48
RMS dz = 66.7158152165
100cm = 87.888162658 percentile value of dz