I mention this because the article seemed to assume that people were buying by the box, and only evaluating price per box, ignoring the weight. Price per weigh

I mention this because the article seemed to assume that people were buying by the box, and only evaluating price per box, ignoring the weight. Price per weight only partially solves the problems... lots of products aren't directly comparable in the first place. For example, 100g of product X is not like 100g of product Y. It works well enough with things like raw ingredients (flour, oil, etc) but even once you are talking about things like cereal, jams, mayonnaise, etc. it starts to break down. It also doesn't work well with meat.