I was walking back from the post office yesterday afternoon when I saw a young woman coming down the stairs extremely slowly. She was seated on the stairs, scooting down one step at a time while hanging onto the handrail. Next to her was a pair of crutches, and she had a cast of some sort on one foot. Nearly immediately I knew that she was our new upstairs neighbor, and figured out what all of that stomping must have been about.
I introduced myself and asked if she lived upstairs, and she explained that she had moved in about 2 months ago. She recently broke her foot, so she's been hopping around upstairs! She apologized about possibly causing disturbances for us. She figured we must hear her, being directly below her apartment.
Anyway, I couldn't stop laughing to myself afterwards. This information makes the noise much more easy to tolerate. So much for my career as a detective.