I remember "How Not To Sort By Average Rating" by the same author, which I am confident helped shape thousands of recommendation/quality sorting algorithms (including Reddit or Yelp), over the years that followed its writing.
Oh, this is a great read! I fondly recall a meeting with extremely bright individuals, and several of us were able to deduce the scale on the fly using the Riemann Zeta Function trick. The presenter was not pleased (the deduced number was not exactly complimentary to their messaging).
> In the absence of calamity, fortuitous events, or brilliant new marketing strategies, sale counts are well-described by a Poisson process. That is, you can think of there being an underlying average number of sales per day, and each day will be a realization of a Poisson distribution with that average.
Can someone give a bit more justification for this? It seems like the average rate shouldn't be constant and is heavily dependent on time/date.
If not, is there another justification for why sales mean should equal sales variance?