Mr. Eric T. Peterson (Web Analytics Demystified) and Mr. Joseph Carrabis (NextStage Global) wrote a new white paper about visitor engagement.

For those of you who do not know the old formula, this is how it used to like look before their new whitepaper:

and this is how it looks now:

We strongly recommend to read this document since it is one of the most accurate articles written about measuring the immeasurable. You can download the white paper from here.