The Merritt-Clifton study has been dismissed by many experts as being biased and unreliable. The CDC study is a much better one to go by, although they do admit that it is faulty also. Their reasons were because the source information came from media reports, which are notorious for over-reporting on dogs whose breed is considered controversial, misidentifying breeds, and omitting important details about the history of the dog.
Dogbitelaw and Dogsbite.org are not considered reliable because they both carry a bias. Also, one is run by a lawyer, and the other by a web designer who was known as “bitbypit” a full year before she was allegedly attacked. Some things to keep in mind.