Yahoo! Shopping displays the number of ratings that are used to calculate the Overall average rating.

More information:

• What are merchant ratings and reviews?
• What does a merchant rating look like?
• How is the “Average Merchant Rating” calculated?
• Is every merchant rated?
• What does the “Buyer Protection” icon mean?
• What does “Not Yet Rated” mean?
• What does it mean if a review is from a “post transaction survey?”
• How do I submit a merchant rating and review?
• Can I submit more than one review for a merchant?
• What are the guidelines for writing a review?
• Can I include links or other HTML in my review?
• Why isn’t my review showing up?
• How often are merchant ratings and reviews updated?
• How do I report an abusive, off-topic, or otherwise objectionable review that I think should be taken down?
• Can I edit or delete my review?