By choosing to charge clients on a per-qualified-lead-generated basis, Growlabs becomes a realistic option for smaller businesses that otherwise might not be able to afford a costly, SaaS-only, subscription. Raffi told me that Growlabs' smallest clients typically use the service to send a few thousand emails per month, and larger clients have used it to push 20 to 30,000 emails.

A Bayesian network is a compact, expressive representation of uncertain relationships among parameters in a domain. In this article, I introduce basic methods for computing with Bayesian networks, starting with the simple idea of summing the probabilities of events of interest. The article introduces major current methods for exact computation, briefly surveys approximation methods, and closes with a brief discussion of open issues.