I was at the vet a while back; one of my dogs wasn't well (she's better now). The vet took her back, and after waiting for a few minutes, the vet came back with her.

Apparently there were two possible diagnosis: let's call them x and y, as the specifics aren't important for this anecdote.

The vet specifies that, based on the tests she's run, she cannot tell which diagnosis is accurate.

So I ask the vet: which diagnosis has the higher base rate among dogs of my dog's age and breed?

The vet gives me a funny look.

I rephrase: about how many dogs of my dog's breed and age get diagnosis x versus diagnosis y, without running the tests you did?

The vet gives me another funny look, and eventually replies: that doesn't matter.

My question for Lesswrong: Is there a better way to put this? Because I was kind of speechless after that.