I was surprised to have access to this group. I suppose you can ban me at any time, but also you can just tell me when I'm not being helpful.

I was surprised when studying for an education degree that the course in Educational Evaluation was one of the most challenging and interesting to me.

In terms of instruments for evaluation reliability is a quantitative measure whereas validity is a qualitative measure. Both are very important, but certainty about validity is much trickier than for reliability.

My sense is that far from needing to be saved from subjective results, there's no choice but to go deeper down that rabbit hole. As far as it goes with ill-defined words, precision is something to strive hard for, but the problem comes with trying to nail down creative and growing processes. Some real and important qualities will never be precisely defined because they are growing qualities.

Other words are not able to be defined sufficiently; for example left and right. As I say, precision in definitions is important, I just think there's a wall you eventually run up against. And facing that wall is the only way to make progress in your tasks at hand.

I do so admire Peter Drucker, but his aphorism distracts from this problem I'm alluding to. Measurement is important, but somethings cannot be measured because they're not "stuff" of matter and weight. That's not to say there's nothing we can say, rather to suggest there's some other ways besides measures.