Not consistent data on the DataGraph

[pierafal]

The Problem

I'm using -3 decimal shift to have the result in m3 (not litres). My readings are like:

4 most significant digits represents m3 and 3 least significant digits are litres.

The Data Graph shows incorrect values for change rate (blue bars) that are not consistent with Value (green line)
In this example ~10:00 the green line show change from 42,743 to 42,747, which is 4 litres, but the change rate shows 0,0008.

Version

b72d809+

Logfile

no logs

Expected Behavior

No response

Screenshots

No response

Additional Context

No response

[SybexX]

the "change rate" is the change in value per minute (m3 / min) >>>> 42,747 m3 - 42,743 m3 = 0,004 m3 >>> 0,004 m3 / 5 minutes = 0,0008 m3 / min

[pierafal]

ok, so it's kind of Usage Velocity. The Change description with no unit of measure is misleading.
How is it calculated? What is the time interval?

[SybexX]

change rate = (PreValue - Value) / (time - timeStampLastPreValue)