CJ, I use a simple one when involved in aircrew safety related training.
Simply put, it is the product of skill and experience.
No amount of skill will guarantee an appropriate result. Conversely, no amount of experience can make up for a lack of adequate skill or proficiency. Both go hand in hand.
As an aside, I dislike referrals to a negative outcome as, 'He/she exercised poor judgement'. A persons decision, actions, or inactions are based or exercised on their perceptions, correct or incorrect, at a particular moment in time.
'Poor' judgement is subjective. Monday moring quarterbacks are always blessed with hindsight.
As a very wise Captain says, 'There but for the grace of god go I...'
For what its worth.
...by the way...
I, too, recommend Tony Kern's books....