curvature versus slope
  n = 157934 
  X=0, Y = 33.74 +/- 16.40 
  Weighted least-squares fit:  Y = 38.4 + 3.217 X  + -0.03459 X**2 

slope versus dZ, curvature < 5
  n = 93161 

  Weighted least-squares fit:  Y = 69.3 + -1.240 X  + 0.01223 X**2 
     at X = 100, Y = 67.6 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 131102 

  Weighted least-squares fit:  Y = 69.2 + -1.217 X  + 0.01260 X**2 

curvature versus dZ, slope < 10
  n = 9074 
  X=0, Y = 56.93 +/- 8.62 
  Weighted least-squares fit:  Y = 56.6 + 1.632 X  + -0.27463 X**2 


Number of samples 158935
Max dz = 900
Mean dz = 47
RMS dz = 89.3084542471
100cm = 96.4815805203 percentile value of dz