Colby's actuarial career has mostly focused on healthcare with additional disciplines including software, finance, and employee benefits. He consults clients on financial risks, assess and manage operational risks within an enterprise, advise on funding levels and pricing, use modeling and data analysis techniques on large data sets to discover predictive patterns, perform experience studies, and conduct cash flow testing and financial reserve valuations.

Much of Colby's actuarial focus has been in the public sector with state government sponsored healthcare such as assessing and managing the financial risk for Medicaid programs through MCO capitation rate development, health reform modeling, and modeling out the impact of value-based purchasing initiatives such as ACOs and PCMHs.