“Bought Together” is a Product Recommendation strategy that recommends complementary products that are typically purchased together with the product currently viewed.
“Bought Together” Strategy Explained
The Bought Together recommendation strategy operates within the context of either a single specific product in view, or a list of products (i.e. the current user’s cart), offering other products that were often purchased in the same cart as the product/s in focus. Similar to other recommendation strategies, it is based on a heuristic (assumption): commonly bought-together items are complementary to each other, and so offering them in context may increase the user’s cart size and average order value (whilst other strategies are more geared toward offering substitute products or personalized recommendations. Of course, what is considered a substitute for one might be considered complementary for the other, even as each strategy is an “educated guess” on the user’s perception of the presented).
The Idea Behind the “Bought Together” Formula
When one gives the “Bought Together” heuristic a casual thought, it seems to make sense that all one need to do is to sort all other products according to the number of times they appeared in the same cart with the product in focus, and simply serve items from the top of that list.
On second thought, though, as some products are generally popular (e.g. socks in a clothing store, or milk and eggs in a supermarket) they would appear in the widget all the time – since they are practically bought with anything. In effect, these items would “steal” precious screen real-estate from the less obvious answers to the question of bought together: items that might be less popular in general, but have a stronger “link” to the product in context. “Link” is of course a vague term, but the formula detailed below puts that in concrete terms.
A good “Bought Together” formula, like the one used in Dynamic Yield, strives to strike a balance between those items that are generally popular (and are, in absolute terms, the most frequently bought-together with the current item) and those which are less generally popular but are a good match to the specific item now in view.