check_devices.sql

select 
  device, orientation, AVG(x) as avg_x, AVG(y) as avg_y, AVG(z) as avg_z 
from
  still
where 
  device like 'LG%' 
  and orientation = 'onback' 
group by 
  device, orientation

device       |orientation|avg_x                  |avg_y                  |avg_z                 |
-------------|-----------|-----------------------|-----------------------|----------------------|
LG-Nexus4    |onback     | 0.12432878686215066961|-0.17218347813557426799|9.88298942855441278522|
LG-Optimus-2X|onback     |-0.24251323957198989615| 0.35219223021891664328|9.58435814538310412574|
LG_G-Watch   |onback     |-0.09626473196679885943|-0.22697305557692307692|9.82735868279882665268|