BQ27510-G3: How to evaluate the Accuracy of a Battery Fuel Gauge System

I am applying  the BQ27510-G3 in my system and I have a question that is How to evaluate the Accuracy of a Battery Fuel Gauge System?  I find soc error cannot reflect the real accuracy of a Battery fuel gauge system, I  have two goldfiles , one of which our system can use 3.5h, another can use 4h, because the fisrt one's current is not very Accurate, but we calculate the SOC EEROR of two files, both of them are very low, <3%, so  I am very confused