one of my staff has 68% Quell Speed
and the tooltips says 68% of Quell Speed modifier will give you
+51.52% Quell Speed out of [+0.00|100.00].
So if I learned math from elementary school correctly
100%-0%=100%
and the modifier rate goes 0% to 100%
Shouldn’t 68% modifier be 68% Quell Speed and not 51.52%?
Is there another calculation that I don’t know? or is the tooltip wrong?
ill assume one is , but it could just be a new field of maths , Fat shark maths.
could also be wighted around the middle ground so that say 80% of staffs fall in the middle 60%
id cal it even odds an any of them or others 
The stats do not necessarily translate 1:1 into bonuses.
The effect of a 10% increase in the stat can be different, depending on the increase being from 10-20% or from 70-80%.
Think of 10% of the population holding a certain % of the overall money. The top few % hold more money than the bottom few %.
Same with the impact of the stats on weapons.
It can be a bit confusing (like a few other things in this game), but that is how it is.
That kinda make sense but I still want to know how it is calculated
but shouldn’t they distribute the increase rates even?
They could, and you could make the argument that they should, but apparently they did not (at least not in all caases).
At the same time you could make an argument FOR the effect of the bonus % not being equally distributed, as it is for the quell speed for example.
This way, even a small bonus % increase at the top end can make a relatively big difference and still make small upgrades in bonus % relevant.
For example, if you have a base damage of 100 and get a 1% increase (-> 101 dmg) it is a simple 1% more than before.
However if you already have 99% dmg increase (199 dmg) and then get 1% extra (-> 200 dmg), that is now only a relative increase of 0.5025%. Increasing the effect of the top % can make them still have a noticeable impact.
Although i would not generally disagree with this idea, i find that it makes the entire system a bit less digestible and also, with the pure rng system that we have for item acquisition, it is just an annoyance to get upgrades in general.