As has been pointed out by many people before, performing a least-squares fit to the logarithm of a histogram in order to fit a power law is fraught with danger. The principal objection to the method is that the statistical fluctuations in the logarithms of the data are greater in the downward direction than in the upward one. This effect is more pronounced in the tail of the power law, and this has the result that there is a systematic tendency for least-squares fits to overestimate the slope of the power law.