Compa-Ratio - Base vs Overall

Summary:

I know the Compa-Ratio is derived based on salary / midpoint. The question is what is the seeded "salary". Is that salary the overal rate of pay or is it the base rate of pay. Referring to the below is the compa-ratio salary($20) / midpoint($20) = 1.00 or is it overall($22) / midpoint($20) 1.10?

Base = $20/hour, Shift = $1/hour, Leader = $1/hour & Overall = $22/hour...... Midpoint $20/Hour...

I have seen other forum postings and from what I have gathered the seeded salary being used is to be Base($20) but we are seeing it to be using Overall($22). We just migrated to pay components instead of just one component.