• by Joe Mandese  @mp_joemandese, May 15, 2012

Matt Goddard, CEO of R21, just gave a nifty guideline for vetting the opinions of all those social gurus offering you advice about products, services and brands. If you’re surfing social opinion sites, he said, sample sizes matter.

“If 30 people mention information on a website, that means it’s true,” he said, offering an rule of thumb that social media insiders apparently know to be true. To back that up, he got a second opinion form OMMA Social panel moderator, Dr. Augustine Fu, who is also founder-ceo of Marketing Science Consulting Group.

“Thirty is kind of a magic number,” Fu confirmed.

Alas, there were only five people on the panel, and the others didn’t way in, so there’s no way to know if what Goddard and Fu said was actually true, but if you want to heed his advice, go ahead, because as Goddard says, “If you have large sample sizes, that means the information is usually true.”