The bias-variance tradeoff is a specific topic that isn't quite the same as bias or variance (although they obviously overlap). It seems like questions about it are thus somewhat distinct. I wonder if it would be better to have a specific tag to group these questions. At present, we have 124 threads with both tags and another 15 that have only one of the tags plus the word "tradeoff". This implies we may have something like 140 threads on this topic (compared to 634 threads with bias and 2374 with variance).
With no meaningful opposition to this, I'm going to go ahead and create a bias-variance-tradeoff tag and begin the process of retagging.