I hit on that with the last sentence. It's hard, and it's easy to create unfairness the other way. It's also easy to create perceptions that student B only got on the team because they are female, black, poor, or whatever.
At the same time, when student B shows up, and is nearly as good as A despite almost certainly having less chance to practice... maybe B is actually a better talent and will be better overall.
Making qualitative decisions sucks. But sometimes a holistic, qualitative decision captures better what is going on than the strict quantitative "fair" measure. It's all fuzzy and difficult.
I will say, especially with youth: my "fair" measures have been rubbish at predicting performance. Some of the strongest students on my robotics teams and in challenging classes have been the ones that did not look like it on my first measures.
At the same time, when student B shows up, and is nearly as good as A despite almost certainly having less chance to practice... maybe B is actually a better talent and will be better overall.
Making qualitative decisions sucks. But sometimes a holistic, qualitative decision captures better what is going on than the strict quantitative "fair" measure. It's all fuzzy and difficult.
I will say, especially with youth: my "fair" measures have been rubbish at predicting performance. Some of the strongest students on my robotics teams and in challenging classes have been the ones that did not look like it on my first measures.