Overall Network Quality

Question

After end call I monitored an overall quality  rating  sometime 4.49/5.0 or 5.0/5.0.  but the detailed stats in both cases 

lost packets = 0 and jitter = 0

I would like th known the calculate method for application to use for Overall Network Quality.

Comments

I'd like to underline a little loss of information regarding "overall network quality" on the new Zoiper Beta for Android.

After a call this number is either 5.0 or 4.0 (I guess 3.0 and 2.0 for very bad quality). It looks like the calculate number is trunced to the first digit. The former version (non Beta) provided one or two digits more (I don't remeber).

I'd appreciate the former precision of this quality indicator (with low priority of course).

Zoiper Beta for Android 2.2.29 Lib.rev. v2.8.70-mod. Android 6.0.1.