As you suggested this approach sort of works, as does simpsons (using 5,8,-1 rule)
But does not seem to handle negative acceleration well.
I tried a simple dataset ( moving the accelerometer vertically over a known distance)
and all of the proposals seem to work for +ve accelerations but as the accelerometer slows, -ve accelerations appear as could be expected, summing the integrated velocity results in excell itteratively the velocity rapidly becomes negative. I know this is not the case as the accelerometer only had positive displacemnt and therefore positive velocity.
any suggestions as to where to look ???