The Setterfield thesis that the speed of light (c) has decreased over time is examined from the perspective of Statistical Hypothesis testing. The Student’s t test, the Mean Square Successive Difference (MSSD) test and the Run test show strong support for time variance not only for ‘c’ data but also for c-dependent quantities. No support is found for time variance of c-independent quantities. An examination of statistical work of T. Norman, G. E. Aardsma, D. R. Humphreys, and R. H. Brown reveals some weakness in the statistical supports for their arguments. In addition, some comments are made regarding considerations of Setterfield’s theory.