There are many reasons to use measurement in homelessness work, for example determining the scope of the problem, understanding progress, and using data to make better decisions and set strategy. While attempts at enumeration of homeless people are often controversial, the production of reliable estimates is a critical component in progressive policy development.

There are many methods by which cities and countries measure homelessness, including but not limited to the "capture/recapture" method, surveys based on past experiences of homelessness, telephone surveys, service use reporting, street counts such as Point-in-Time counts and Registry/Connection Weeks, and databases maintained in real time through outreach and coordination with service providers.¹