| 摘要 |
<p>A system and methods are provided for serving content in response to content queries or requests. When a request is received, for content to be presented to a specified user, candidate content items are identified, possibly based on matches between attributes of the user and attributes of the items' target audiences. For each item, a history indicating the frequency (e.g., total number) and/or recency with which impressions of the candidate item were previously presented to the user is retrieved and used to determine a modifier value, which is applied to a calculated or generated probable click-through-rate (pCTR) to produce a modified probability that the user would act on the item if it is served to him or her. Each item's estimated value is computed by multiplying a bid associated with the item and the modified probability; the results are ranked and the top-ranked item(s) are served.</p> |
