Linear acceleration from metabase android app

Hi everyone,

I have recently started to use the metamotionR with the metabase app. This is my sensor:
Firmware: 1.4.4
Hardware:0.3
Model number: 5

I have tried to get the velocity from the linear acceleration of the Z axis but I have seen that when the device is completely stationaty in a table, the values of the linear acceleration (g) of the Z-axis are so high. Here I am attaching an image when the raw data is taken from the device, sampling the linear acceleration at 100HZ.

I have some questions:
-Why I am getting these big accelerations in Z axis? If you take a look to the other axis, they are much lower.
-How can I solve it?
-What does "linear acceleration" outputs?

I wouldn´t like to start developing any code until I see if it is reliable for muy particular aplication. So in a first instance, I have started to work with the raw data and excel.

Thank you so much,

I have have done another try just straming the "accelerometer" at 50HZ, and take a look to the results:
When I have the device stationary face up, the mean acceleration in the Z axis is 1.013G, when it should be something next to 1G.
When I have the device stationary upside down, the mean acceleration in the Z axis is -1.005 , which is less.