curvature versus slope
  n = 207233 
  X=0, Y = 54.50 +/- 19.40 
  Weighted least-squares fit:  Y = 61.3 + 1.824 X  + -0.01990 X**2 

slope versus dZ, curvature < 5
  n = 26087 

  Weighted least-squares fit:  Y = 83.6 + -1.493 X  + 0.01313 X**2 
     at X = 100, Y = 65.7 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 75542 

  Weighted least-squares fit:  Y = 82.8 + -1.380 X  + 0.01265 X**2 

curvature versus dZ, slope < 10
  n = 611 
  X=0, Y = 83.29 +/- 27.96 
  Weighted least-squares fit:  Y = 79.6 + -3.843 X  + 0.66616 X**2 


Number of samples 209956
Max dz = 900
Mean dz = 69
RMS dz = 117.123866056
100cm = 80.2687229705 percentile value of dz