April 22, 2021

Where in the world is all the evidence on what works and why in homelessness?

Have you ever wondered where evidence supporting Housing First comes from, or whether the UK has produced evidence that mental health treatments work for people experiencing homelessness? Our updated  Evidence Finder shows clearly where studies evaluating homelessness interventions exist, and includes 394 effectiveness studies and 275 implementation studies from our evidence and gap maps. The 2021 edition of the Finder includes 196 more evaluations than were in the 2019 edition. 

The Finder now allows users to filter by types of studies, quality, interventions, outcomes, when they were published, among others. These filters will help make it quicker and easier to find the studies you need.


How do I use the map?

Zoom out to get a global view of the research base, and zoom in for a much more local view. Use the filter button to find the research you’re looking for, whether that’s UK-based effectiveness research, high quality evaluations of employment interventions or studies published in the last five years. 

We update the list of studies included in the map annually. The 2021 update for the Evidence Finder reflects this refreshed list

What does it tell us?

The Evidence Finder shows us where evidence comes from and, crucially, where more evidence is needed. Some of the things we learnt from mapping the evidence base are: 

Most of the evidence is from the USA. North America accounts for 85% (337 studies) of effectiveness studies (i.e. research on ‘what works’) and 38% (104 studies) of implementation studies (i.e. why does it work or not). The balance of studies in the finder indicates that the UK has a greater tradition of conducting implementation research than conducting effectiveness research - the UK accounts for 27% (73 studies) of implementation studies but just 7% (26 studies) of effectiveness studies. 

The number of studies being produced has increased rapidly in recent years. 46% of all effectiveness studies were published after 2015. 65% (17 studies) of the effectiveness studies from the UK were published between 2018 and 2020. Similarly, 47% (130 studies) of implementation studies were published after 2015. 46% (33 studies) of implementation studies from the UK were published between 2015 and 2019. 

North America produces more high quality primary studies on effectiveness than the UK. 21% (66 studies) of primary studies from North America are of high quality, while 15% (4 studies) of primary studies from the UK are of high quality. Overall, the quality of the evidence base is mixed. Over 50% of effectiveness studies are rated as low confidence due to methodological problems, with 25% rated medium confidence and the other 25% high confidence. This suggests that while the number of studies is relatively large, there have been methodological challenges that undermine confidence in some of the findings. This underscores the need to invest in more, better studies of effectiveness. Similar methodological challenges have been seen in implementation studies.

What’s next?

We’ll continue to update our evidence finder, adding in new studies. If you have any studies to add to the finder please send them to, with the subject 'Study for homelessness map'. 

Try our Evidence Finder today. If you have any questions or feedback contact us on


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