We have new metrics from Facebook today on the performance of certain Facebook Platform viral channels. All app developers are now able to compare the net performance of their invitations and notifications against the weighted median of all applications.

Here are the new median numbers for all apps on the Platform as of March 10:

Request/Invitation Stats

• Accepts per Action: 14.953%
• Ignores per Action: 84.520%
• Blocks per Action: 0.476%
• Force Invites per Impression: 0.001%

Notification Stats

• Spam Reports per First Impression: 0.041%
• Hide Alls per First Impression: 0.437%

It’s important to note that while almost 15% of all invitations acted upon are accepted, these numbers do not indicate what portion of overall invitations sent were acted upon or accepted. If the stats were actually per send instead of per receiver action, the numbers would be much lower.

It’s also interesting to note that about 0.5% of all invitations cause users to block all future requests/invitations from the app, and about 0.5% of all notifications cause users to “hide all” future notifications from that app.

(For further explanation of how these numbers are calculated, see developer notes here and here.)

For those comparing viral growth on Facebook to traditional channels like email, these numbers offer interesting comparison points. Like email, I would guess that click, conversion, and opt-out rates for Facebook invitations and notifications vary greatly by application type/vertical. How do your Facebook stats compare to your email campaigns?