Six intensity groups with \sim 150 BATSE gamma-ray bursts each are compared using average emissivity curves .
Time-stretch factors for each of the dimmer groups are estimated with respect to the brightest group , which serves as the reference , taking into account the systematics of counts-produced noise effects and choice statistics .
A stretching/intensity anti-correlation is found with good statistical significance during the average back slopes of bursts .
A stretch factor \sim 2 is found between the 150 dimmest bursts , with peak flux < 0.45 ph cm ^ { -2 } s ^ { -1 } , and the 147 brightest bursts , with peak flux > 4.1 ph cm ^ { -2 } s ^ { -1 } .
On the other hand , while a trend of increasing stretching factor may exist for rise fronts for burst with decreasing peak flux from > 4.1 ph cm ^ { -2 } s ^ { -1 } down to 0.7 ph cm ^ { -2 } s ^ { -1 } , the magnitude of the stretching factor is less than \sim 1.4 and is therefore inconsistent with stretching factor of back slope .