Abstract: Electronic marketplaces offer a variety of items to customers over the Internet. Where two or more items are interchangeable with or equivalent to one another, such items may be utilized in the same applications and in the same manner, and marketed and sold together as interchanges or equivalents. Such items may be identified as interchangeable with or equivalent to one another based on a qualitative or quantitative score, which may consider any available information or attributes regarding the items, and may increase or decrease over time as the confidence in a determination of interchangeability or equivalence improves or declines. Moreover, such information or attributes may be identified from any source, such as sellers, vendors or manufacturers of the items, and qualitative or quantitative scores indicative of the accuracy or reliability of such information or attributes may be assigned to such sources, as well.