Normalized flux averaging (NFA) is a simple method of pulse structure analysis. The equivalent pulse width of the main pulse and the time intervals between pulses are defined at the same dimensionless level for every burst time history. Distributions of parameters are compared for different brightness groups of GRBs. If gamma-ray bursts of the same particular brightness group are at the same cosmological distance then all time scales resulting from the emission mechanism must be stretched by the same amount in the observer’s reference frame. Time intervals between separate pulses and equivalent pulse widths represent different physical time scales of the emitters. Using these NFA based parameters, the stretch factors for different brightness groups of bursts are found. ©1998 American Institute of Physics.