Imagine that you are responsible for placing targeted product advertisements on an e-commerce store that you help run. The goal is to analyze a visitor's past shopping trends and select products to display that will increase the shopper's likelihood to make a purchase. Given then the gift of foresight, you've been collecting 50 different metrics on all of your shoppers for months: you've been recording past purchases, the product categories of those purchases, the price tag on each purchase, the time on site each user spent before making a purchase, and so on.
Believing that ML is a silver bullet, believing that more data is better, and believing that more training of your model is better, you load all 50 dimensions of data into an algorithm and train it for days on end. When testing your algorithm you find that its accuracy is very high...
