Calculate Z scores

Let's coalesce all our knowledge of M Language as well as the other skills you've gathered in this chapter to categorize the products in Northwind Trader's catalog based on the price. It is very useful to know how our product offerings are positioned to our customers. This same technique can also be applied to find outliers in your dataset!

We want to know how expensive or cheap each product is compared to the average of products in a category so that we can categorize them based on price, not the kind of product. In order to do this, we will use a statistic called the Z score to evaluate how many standard deviations away from the mean is a particular product's price from the average category price.