curvature versus slope
  n = 2583728 
  X=0, Y = 21.53 +/- 17.41 
  Weighted least-squares fit:  Y = 35.7 + 3.163 X  + -0.03308 X**2 

slope versus dZ, curvature < 5
  n = 420621 

  Weighted least-squares fit:  Y = 49.2 + 0.148 X  + -0.00170 X**2 
     at X = 100, Y = 46.9 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 741751 

  Weighted least-squares fit:  Y = 48.8 + 0.106 X  + -0.00084 X**2 

curvature versus dZ, slope < 10
  n = 274312 
  X=0, Y = 51.88 +/- 36.87 
  Weighted least-squares fit:  Y = 49.9 + -0.545 X  + 0.02343 X**2 


Number of samples 2599451
Max dz = 900
Mean dz = 50
RMS dz = 70.6540869306
100cm = 87.6396592973 percentile value of dz