While we do know that kale smoothies (and drinks overall) are not driving a lot of revenue, we don't know why. A big part of data analysis is implementing your own metrics to get information out of the piles of data in your database.
In our case, the reason could be that no one likes kale, but it could be something else entirely. To find out, we'll create a metric called reorder rate and see how that compares to the other products at SpeedySpoon.
We'll define reorder rate as the ratio of the total number of orders to the number of people making those orders. A lower ratio means most of the orders are reorders. A higher ratio means more of the orders are first purchases.