As opposed to branded terms, the universe of category keywords is understandably the largest on Amazon, with new relevant terms developing over time. In this larger and more dynamic environment, it’s important that you set bids based on the expected conversion rate of a given term.

The issue here, which I’ve written about in a previous column, is that over 90% of category keywords do not get more than one click per day, given a constant bid. Additionally, with roughly 80 clicks being necessary to get a confident estimate of the true conversion rate of a given keyword, running this test could take nearly two and half months. Meanwhile, conversion rates change roughly every month – as one extreme example, think of the expected conversion rate for “easter candy” in April versus May or June.