Non-Fiction

Here's what I was talking about above, though this is not the only such service:


https://www.businessinsider.com/most-valuable-celebrity-endorsements-2011-10?op=1


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The Most Valuable Celebrity Endorsements

Ever wonder how celebrities get chosen for ad campaigns? It's based on research of how much you, the public, responds to them.
Celebrity DBI is an "independent index for brand marketers and agencies that determines a celebrity's ability" to influence endorsements. The index evaluates celebrities based on their awareness, appeal and relevance to a brand's image, and influence on consumers....




https://celebritydbi.com/media/buy-product-here-blake-shelton-yes/

Celebrity DBI

"Among the other fun facts in the Celebrity DBI’s quantification of
stardom, culled from a weekly online survey of 1,000 Americans ages 13
to 75, Swift has a public awareness ranking of 92%, second among
country stars to Dolly Parton, who is known by 95% of survey
respondents.".