Don't use Google Keyword volumes as a surrogate for Amazon Search Volumes
Several years ago Amazon actually published the search volumes used by retail consumers when looking for products. This was very useful information when researching keywords to use for listing or campaign optimization. However Amazon no longer publishes such data, and only publishes the relative search term ranks in each marketplace, and within each department, and then only making such data available to vendors or those sellers with Brand Registry status. Merchant AI needed search volume information for campaign critiques because we frequently find poor keyword choices when benchmarking advertising agency performance. WIthout decent Amazon keyword volume estimates, campaign designers may not generate the target ad impression volumes, and perhaps completely miss the most cost effective keywords for their products. Additionally we also wanted a solid measure of search volumes to derive search-weighted share of shelf metrics for competitive analysis e.g. brand performance.
In the absence of the absolute numbers for Amazon search, many users and services have reverted to using Google Keyword Planner which published keyword volumes monthly. So how does it compare?
In a word -- poorly -- as a substitute for on-Amazon volumes. Here's a plot of Amazon rank against select generic keywords (i.e. unbranded) drawn from consumer electronics categories in the UK for Dec. 2022.
Intuitively you'd expect to see some form of exponentially declining curve starting in the top left and headed to zero in the bottom right. After all, Amazon is the definitive source of their ranking data.
Evidently the correlation is pretty poor. Some Google KW volumes are next to nothing, while others are many multiples of where a best fit line might lie.
So what? Evidently people search differently on-Amazon vs. off-Amazon. When using keyword volume estimates, you need the right source for the job. For AMS campaigns on-Amazon, use the Search Term report that is only available now via API download. For off-Amazon DSP campaigns, then Google KW planner is better placed.
Our research of about 10 commercially available products suggests at least 7/10 purport to give Amazon search volumes based on Google data. Feel free to do your own due diligence.