In this note, parameters used in characterizing the theoretical joint distribution of the periods and amplitudes of sea waves are evaluated in connection with an empirical fetch-limited wave energy spectrum formula derived from wave data recorded in the Great Lakes. The results show that the spectral width parameter obtained from the empirical formula justifies the narrow spectrum approximation used in the theoretical distribution. Further empirical data show that the average wave periods calculated from an energy spectrum are quite close to those estimated from the statistical data.