curvature versus slope
  n = 403286 
  X=0, Y = 12.33 +/- 7.61 
  Weighted least-squares fit:  Y = 12.2 + 1.343 X  + -0.03124 X**2 

slope versus dZ, curvature < 5
  n = 199213 
  X=0, Y = 21.80 +/- 25.29 
  Weighted least-squares fit:  Y = 50.5 + 0.319 X  + -0.00762 X**2 
     at X = 100, Y = 6.2 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 318552 
  X=0, Y = 22.82 +/- 26.36 
  Weighted least-squares fit:  Y = 50.2 + 0.264 X  + -0.00644 X**2 

curvature versus dZ, slope < 10
  n = 197469 
  X=0, Y = 52.68 +/- 22.46 
  Weighted least-squares fit:  Y = 52.4 + -0.765 X  + 0.08967 X**2 


Number of samples 403304
Max dz = 170
Mean dz = 46
RMS dz = 52.2206855566
100cm = 97.8510007339 percentile value of dz