There’s a big difference in being credible and being successful. Very few self-published authors are both. Credibility lends toward a properly edited and formatted book in the self-publishing world. As credibility relates to traditional publishing vs. self-publishing, it’s all about money which is pretty much the bottom line for every author whether they admit that or not. Some may disagree. I say take a look at Amanda Hocking who was the first self-published Kindle author to make a million dollars. This got her the attention of a traditional publisher and she took them up on their contract. Was she credible? Yes. Was she successful? Let the size of her bank account (before or after her traditional contract) answer that. If you are worried about credibility, it’s because of the stigma that still comes with being a self-published author. If you take the time to properly edit, format, and market your book, credibility won’t be a problem. It’s the success of your book that you’ll still be judged by.