Barry Setterfield, an Australian creationist, published his theory that the speed of light has decreased over 20 years ago. He produced evidence from historical observations of the speed of light and other "constants" of physics. It's amazing how science keeps on proving the truth of creation. Sadly for him, this is not the same phoenomenon that he predicted. As it were, his predictions are easily questioned by looking at the number of significant figures that the observations he uses relies on. I hear he posts frequently to the Baptist Board (www.baptistboard.com). I posted there before the environment became much too hostile for a productive crevo debate to occur.
Its interesting that you question the data. Lambert Dolphin, a physicist at Stanford, teamed up with a professional statistician, Alan Montgomery, and ran the proverbial fine-tooth comb through Setterfield's paper to check the statistics used. They published their findings in defense of Setterfield's work in
Galilean Electrodynamics, Vol 4 No. 5, pp 93ff., 1993. This has never been refuted in any journal or conference.
Moreover, in Oct 1975 Scientific American, (pp 120), C.L. Strong questioned the constancy of of the speed of light "as science has failed to get a consistently accurate value."