curvature versus slope
  n = 4118196 
  X=0, Y = 38.57 +/- 30.66 
  Weighted least-squares fit:  Y = 57.1 + 1.879 X  + -0.01919 X**2 

slope versus dZ, curvature < 5
  n = 42420 

  Weighted least-squares fit:  Y = 85.1 + 0.056 X  + -0.00174 X**2 
     at X = 100, Y = 73.4 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 222911 

  Weighted least-squares fit:  Y = 83.2 + 0.103 X  + -0.00089 X**2 

curvature versus dZ, slope < 10
  n = 16701 
  X=0, Y = 88.04 +/- 44.36 
  Weighted least-squares fit:  Y = 80.2 + 1.904 X  + -0.02578 X**2 


Number of samples 4174350
Max dz = 900
Mean dz = 74
RMS dz = 94.8367017562
100cm = 72.0753650269 percentile value of dz