Interesting that round numbers mean lower selling prices but that the sales happen quicker.
Steve Tadelis is one of the co-authors and he's done some interesting research from his time at eBay. Last year he published a paper that paid search ads were not really effective and that made the rounds, even getting mentioned in The Economist. Google wrote back to refute the claim, saying eBay is a special website and search ads do work. Here's that study: http://newsroom.haas.berkeley.edu/research-news/study-finds-...
For fun you can try out non-integral factorial values. For example, type in (1/2)! into WolframAlpha or Google, and you'll find the answer is the square root of pi over 2.
Thanks. I can assure you the graph is not fake--I would have make a much closer fit if I had concocted the data. The bell curve fitting was done by hand to be suggestive, sorry I did not do an algorithmic fitting (perhaps I should have done more research on this).
If you are using Excel, you should use Average and Stdev to get the parameters and Normdist to draw it. For example, you can read http://excelgraphs.blogspot.com/2013/03/historgrams-and-over... (I don't like how they make the final graphs, but the article explain how to use the functions.) (Be careful, because it's easy to use the wrong x axis, and draw the Gaussian curve shifted 1/2 histogram bar.)
If you like to understand the calculations and use less magical function, you can read http://www.phys.utk.edu/labs/plstatan.pdf . (If you want to read directly the code, go to page 5 to skip the theoretical background.)
I have written ebooks and was considering courses, so let me offer an opinion too. I opted to develop YouTube videos to promote my brand MindYourDecisions. The reason is YouTube has many more users and you have a chance to establish your authority and market books. If you get over 10,000 subscribers on YouTube, you can also make paid subscriptions which you can use to sell courses.
