And when we do that, we lose sight of what matters.
What matters, of course, is whether an item generates profit or not.
I like to simplify things. Roll your data up on a quarterly basis. For instance, measure item performance from January - March. Sum all of your catalog expense across each time the item was featured in a catalog. Do the same thing for search, for e-mail marketing, for all other online marketing activities.
Run a profit and loss statement for each item, during the quarter.
In this case, item #2 did not generate the sales that item #1 generated, but item #2 did generate more profit. This is the type of analysis we need, the type of analysis that is sorely missing in our channel-based, attribution-focused, tweeting-simple-kpi's world.
Focus on how merchandise performs across channels. Spend less time focusing on channels!! Merchandise can sell without channels. Channels cannot exist without merchandise.