curvature versus slope
  n = 281903 
  X=0, Y = 51.24 +/- 32.18 
  Weighted least-squares fit:  Y = 64.4 + 1.382 X  + -0.01388 X**2 

slope versus dZ, curvature < 5
  n = 22753 

  Weighted least-squares fit:  Y = 74.6 + -0.038 X  + 0.00028 X**2 
     at X = 100, Y = 73.7 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 68038 

  Weighted least-squares fit:  Y = 77.0 + -0.102 X  + 0.00109 X**2 

curvature versus dZ, slope < 10
  n = 3590 
  X=0, Y = 71.57 +/- 9.04 
  Weighted least-squares fit:  Y = 72.4 + 0.808 X  + 0.01224 X**2 


Number of samples 284899
Max dz = 900
Mean dz = 88
RMS dz = 114.030697621
100cm = 70.4916479173 percentile value of dz