Analysis of environmental data is never straightforward, and methane emission data from underground coal mines are no exception. In the United States, considerable effort has been expended by the U.S. Department of the Interior, Bureau of Mines, to develop ventilation devices that dilute methane at coal mine working faces. Careful analysis is required to measure the effectiveness of those devices. The most prevalent underground coal mining method in the United States is by continuous mining machine. Research showed that methane emissions during operation of this machine occur as a series of peaks and that concentration peak values will fit a normal or log- normal distribution. It appeared that normal distributions were obtained when the emitted methane was vigorously mixed into the incoming fresh air stream and log-normal distributions were obtained when mixing was less vigorous. The purpose of this paper is to explore that finding in greater detail, as well as to assess the benefits gained by transforming concentration data.