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I'm not sure what dictates a "published study," but I have read countless articles on how important maintaining consistent NAP-info on business listings. But I'm interested in seeing what other people have to say, so I'll comment to follow this thread.

This is an actual client who almost disappeared from Google.

I don't see how they could have gotten hit with a penalty, to be honest. We have been working with them for a while and haven't done anything different. Maybe a few tweaks to meta descriptions / title tags as we update their site.

The client is called Orthopaedic Associates, based out of Boise, Idaho.

You can view their site here: https://orthoa.com/