This study centers attention on the effect of varying lengths of time (weekly, biweekly, monthly observations) on measured demand elasticities for disaggregate fresh beef products. Parameter estimates and elasticities based on monthly data differ from those based on biweekly or weekly data. Generally, inventory adjustment dominates with the latter time intervals. On the other hand, for three of the six disaggregate fresh beef products analyzed, habit formation is the dominating effect with monthly data.