I want to define a KPI that measures the relative amount of freight costs to the amount sold.
The target is to limit this percentage as much as possible, so "decreasing is better".
Let's say that in most cases the freight cost is below 10%.
The best case would be 0% (but unrealistic).
A "good" situation is where we have 5% freight costs.
Bad sales are sales with freight costs above 15%.
What this the best way to model this KPI ? Use a normalized methode, or absolute ? What is the "worst value" ? ..