I think the numbers are very low there, though, because Yext used their diagnostic tool to produce the stats. However, their tool checks for only one listing per site, i.e. duplicate listings are not taken into account. Additionally, their tool doesn't always find listings that actually exist, especially if the information on such listings is too inconsistent. Thus, I would probably add at least 20-30% to the stats they reported.
One notable example of why the research is quite flawed is their reporting of MerchantCircle featuring just 40% "of anything wrong". MerchantCircle is the site on which I consistently find the largest number of duplicate listings, but as I mentioned above duplicates are not taken into account in that research because of the downsides of the tool they have used to gather the data.
However, both of them didn't take into account an important feature such as historical changes in core business details (for example: a business moved to a new address some time in the past), and that is why they are both quite flawed. Specifically the Yelp research is very questionable as the results are quite self-serving.
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