Scoring, or grading, is probably one of the most challenging and confusing parts of the OKR framework.
What is the difference between OKRs and KPIs?
Problem
Current techniques, like only using binary scoring (0/1, True/False) or Google's (0, 0.3, 0.7, and 1.0), can be too simple or too subjective and often illogical. More often than not, without an upfront agreement, the event at the end of the OKR cycle can be messy and harm the OKR adoption process.
The major difference from existing practices is that you agree with the team members on scores upfront - at the time of drafting the Key Result.
I would also suggest using a predictive indicator to keep unpleasant surprises to a minimum at the end of the cycle. When you create a Key Result, it is only natural that your confidence is high. During the recurring check-ins, when you debate the progress, you should mark the confidence level to be different, less optimistic, if the circumstances paint that picture.
Using predictive indicators is a great technique to focus your efforts, change expectations, or even abandon the attempt to complete the Key Result.
The credit for the "Pre-scoring" goes to Ben Lamorte which inspired some of my work on the Agile Tools digital OKR platform for team-oriented modern organizations where there is no room for personal OKRs. #Accountability is achieved within the team