24. The invention of claim 23 wherein combining further comprises: adjusting the preselected period of time in accordance with a quality of the ranked search result set associated with the matching advertisements.
24. The invention of claim 23 wherein combining further comprises: adjusting the preselected period of time in accordance with a quality of the ranked search result set associated with the matching advertisements. 25. The invention of claim 24 wherein the quality is the quantity of the matching advertisements.