How do you measure 'virality' of your content?

There's so much out there on how to measure virality of content, that it gets confusing. So far the best definition, or formula, I have seen comes out this year's SXSW #viralcode sessions, and it has been kind of ratified by Simply Measured as well.

The way we should measure 'virality' of content is by:

Number of Clicks/Impression
x
Number of Shares / Click
x
Number of Impressions/Share
= V

If you get a Viral coefficient above 1.0 your content is viral...
(essentially, each person spreads content to more than one other person)

So, mathematically put, it is:

# of Clicks                   # of Shares                 # of impressions

––––––––––   x    ––––––––––   x       ––––––––––––    =  V

Impression                      Click                              Share

I have also seen this:

Here are a few metrics that need to continuously trend in the upward direction:
# of new views every day (or even every hour)
# of shares or promotes
# of new comments
# of mentions/occurrences outside the original post

and it sounds good.

Compare this measure of virality from SXSW with going viral in epidemiology, where viral in disease is when one person spreads disease ot more than one person. And where contraction x transmission x exposure is the measure. Interesting.

Essentially, what is important in the viral content game is having the right shareable content and the right context. Which really is what engagement is about. Food is engaging – specially on Facebook, no wonder six out of top seven video content publishers on Facebook last month were food related. We heard at #viralcode about platforms. Be mindful of the culture of each platform you use. FB is more about happiness & sharing; Twitter is snarky and funny. Usually. One really needs to speak the native language of the platform. Because each platform has its own culture, it's own 'socialspeak'.

We also heard this: Shareable content = ideal, moral self; identity expression. Clickable = private, actual, [secret shhh] self. This was from Sean Wojcik, a psychologist and research scientist. Made sense. What we are learning is simple... What we click is private & what we share is public. Shareable content  ≠ clickable content - they have different formulas. 

And, yes, there is a science behind it. No wonder that sites like Upworthy have actual social scientists working for them to figure out how/why people share!