About Capture-Recapture

Capture-recapture is a dependent method that organizations can use with other methods. Capture-recapture is effective for tracking changes over time and requires multiple counts. Unlike the other methods, capture-recapture doesn’t have its own required resources, except for time. Capture-recapture tends to have at least two enumerations over an extended period, usually throughout a year. For more information on common methods, please follow the links below: Admin data, PiT Counts, and Registry Week.

Capture-recapture as a scientific framework has a long-standing history in data collection, particularly in population studies. While this method’s name is controversial concerning homeless populations, researchers and scientists widely accept this method under the name capture-recapture. The term retains this name in this toolkit, intending to provide clarity and consistency with other resources and studies.

“Homelessness won’t be solved if all we do is talk about it”

– Amanda (via Invisible People)

Steps To Collect Capture-Recapture Data

When determining what enumeration method to use, determine if you would like to add a capture-recapture component. For example, if you select the PiT method, adding a capture-recapture means repeating the PiT again in a month to determine the accuracy of the initial count.


  • Limitations vary depending on the method used.

  • This method requires short time intervals between observations to ensure a fixed population.

  • Privacy regulations may not obstruct the linking of individuals from different data lists/observations.

Case Studies

The Importance of Numbers: Using Capture-recapture to make the Homeless Count in Adelaide

In this case study, researchers rely on three registry lists of individuals who met the inclusion criteria. The researchers compared the estimation devised from these lists to their 2001 Census data to plan services and policies to support the city’s homeless population.

Estimating Homelessness in the Netherlands using a Capture-Recapture Approach

The Netherlands’ research provides a great example of the capture-recapture using administrative data. By using their high-quality data sets, researchers were able to estimate their homeless population annually. Still, they could also discern other essential characteristics such as age, gender, and origin of the individual.

Questions About Capture-Recapture

For questions, please email

Additional Resources

This collection of resources contains IGH’s sample policies and procedures, to help you choose an enumeration method. Browse by clicking on the links provided to you.

Estimating the Homeless Population: Sampling Strategies

Can we measure homelessness? A critical evaluation of ‘Capture–Recapture’

Estimating the Size of the Homeless Population in Budapest, Hungary

Not sure If this is the right method for you?