Performance Management: Performance Rating Calculation Fast Formula

Summary:

Can anyone share the sample Fast Formula Performance Rating Calculation, that would be great help.

Content (please ensure you mask any confidential information):

The Performance template has 2 sections, first section has questionnaire. Each quetion have ratings to select (Effective, Highly effective, Ineffective)

Section 2 is Overall summary, which will calculate based on the ratings selected in 1st section.

The Fast Formula will be attached in Overall summary section.

I am trying to figure out DBIs that would correspond to those section ratings. And need to write logic how can I refer those DBIs and build my logic.

Any pointer/sample will really be helpful