What determines the length of the success rate bar?

[kingofaces]

I know the quality rate affects this for sure. I heard someone saying you also get better success rates with higher related skills as well. I haven't seen this mentioned before, so has anyone seen anything to back this up? Obviously this is excluding any differences due to quantity/quality.

 

[Strash]

QR matters huge....
Skills to max level


but i always found sometimes when i hit new levels i would get better results maybe just coincidence

 

[Farmer Smurf]

What determines the length of the success rate bar?

Screen resolution, and monitor size