Mashable.com reports:  As a standard formula, ROI is pretty basic, ROI = (X – Y) / Y, where X is your final value and Y is your starting value. In other words, if you invest $5 and get back $20, your ROI is (20 – 5) / 5 = 3 times your initial investment. In the financial sense, ROI is measured purely in the context of dollars and cents, however, the principles can really apply to any type of investment — monetary or not.
Although ROI ≠metrics, traditional web metrics like traffic counts, number of comments, Twitter followers, Facebook fans, etc. are an important component when calculating your ROI.
The trick is to not rely solely on the numbers, but on what the numbers end up leading to. For instance, does your increase in website visitors correlate with higher sales? Are people that find your website from Twitter or Facebook then clicking on your product pages or going to the e-Commerce section of your site? That’s the sort of data you want to be able to look for.
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