@JohnRob
As it's acceleration the units are m/s^2. The true value of the acceleration due to gravity is 9.81m/s^2 but my sensor is inexpensive and gets 9.95 m/s^2 as the recorded value.
I need to be able to calculate the instantaneous velocity at each interval (10 times a second) which will also be used to calculate the instantaneous distance travelled (height) at that point.
The average may be an easier option but unfortunately it doesn't suit the environment that is needed for my project. But this is where the issue is, the instantaneous calculations just seem to either be incorrect (My fault) or something is affecting my program which I just can't seem to understand.
Also, if my accelerometer can measure 16 bits, does that mean it will for each measurement, am I able to truncate it to just 2 d.p in my code and the calculations.
sorry for the long post, thank you for helping 
-Harvey