People ask what is viral? Viral is the ability to add more value to an existing business in the form of people sharing the service with their connections. If the viral growth is over 1, that means that the growth is in full affect. To simplify for example, if a set of # users are inviting more than their # of users, you have a score more than 1. Calculating viral formulas is a science, and every business needs it. However, the formula has to be tailored to what business it's applied to. For that, first data is calculated accurately and presented. From there, patterns are observed and a strategy needs to be developed. The strategy is applied and the measured factors are observed. Sometimes, the duration of the factor is very important. For example, if you are sending out invites, you need to wait a couple of days for the users to receive those invites before taking their statistics seriously.
Retention is also key, because people focus so much on viral and end up spamming the crap out of their users. This creates a disjointed affect in the space, and people feel that they receive too many emails for no reason. Affective email strategy is key. Timely emails can not only increase retention, but also viral growth. Retention can simply be measured by looking at a cohort, i.e. a group of users and determine how many times they are coming back to the site. Retention can be measured not just by users, but also content, for example how much content is being published per month.
Finally, it's key to have a good grasp of your engagement metrics. This is the ability to drill down in various measurement categories, and develop a combined score. For example, for a social networking site, the amount of users, photos, friends, content, time spent, etc. are all key metrics that need to be paid special attention to. If a user wants to upload a photo album and the service fails, chances are that they will upload the photos to a different site and in the future, continue to go to that other site.
To run a successful company, all the above areas should be monitored very carefully and historic data should be looked at for trends. I highly recommend the use of tracking tables and then build summary tables. Groovy on grails is excellent for Java developers, that want to quickly look at database tables and build dashboards. Google charts is also affective way to display charts, without spending a tremendous amount of time learning charting tool kits.
