Another Sherlock Clue

Here's another Sherlock Holmes statistical connection (thanks Laura). This image is from another modern update to Sherlock Holmes. This is from the BBC TV series Sherlock that appears on PBS Masterpiece Mystery. This episode is A Study in Pink a modern version of the Arthur Conan Doyle story A Study in Scarlet. Notice the pattern of footfall placement on the steps. Each step shows a bell-shaped  distribution of wear. You can trace the mode of each step's distribution and see a regression curve of the modal path up the steps.

Arthur Conan Doyle described such a wear pattern in his story The Man with the Twisted Lip where Watson describes his investigation of an opium den:

I passed down the steps, worn hollow in the centre by the ceaseless tread of drunken feet.