Best approach to calculate Impact vs Timing

[W_Von]

I'm trying to generate a bubble quadrant chart, but need to further refine my data. The quadrant will have Impact along the X axis and Timing along the Y axis. The size of the bubble should be the quantity of the Category. My data looks like the below:

Category Issue Description impact Timing
Training Low Short-Term
Inspection Medium Long-Term
Reqmt High Mid-Term
Inspection High Short-Term
Training Medium Mid-Term

I need to develop some scoring mechanism to show where the most impactful and shortest term gains would be to resolve specific issues but show them across the quadrant. Any advice would be useful.

Thanks Bill