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September 1, 2022

Introducing the Third Edition of our Implementation Evidence and Gap Map

Dr Lígia Teixeira

The Centre for Homelessness Impact created evidence and gap maps (EGMs) that capture what we know about what works and why things work – or not – on homelessness interventions, in partnership with the Campbell Collaboration. The latest report represents findings from the third update of the implementation map.

Until recently, there were no reliable evidence tools to help us identify what we know and what we don’t know about ending homelessness for good. Evidence was scattered around different databases, journals, websites, and in grey literature, and there was no way for decision-makers to get a quick overview of the existing evidence base. This acted as a barrier to using evidence to improve outcomes. To address this challenge, we created two EGMs, which are interactive visual depictions of the available evidence on a specific area of study. 

By making relevant studies more accessible to end users, they facilitate evidence-informed decision making. In highlighting areas of high policy relevance where evidence is lacking, EGMs can also help research funders target their resources to fill important evidence gaps faster, more cost-effectively, and in a more strategic and impactful way. Find out more about our EGMS in the video below.

This latest report presents findings from the third update of the Implementation Map, containing all qualitative evaluations of homelessness interventions. When we released the first map, we found just 246 relevant studies across the entire globe. Two years and two editions later, we found 407, demonstrating an encouraging growth in qualitative evidence shedding light on why interventions designed to tackle homelessness work well or not. UK-based studies have similarly increased by 62% since 2014, accounting for 28% of the global evidence base. Over half of the evidence in this map is from North America.

Quantity is no match for quality, however, and the vast majority of the studies included in this update (around 75%) score low confidence in their study findings, highlighting the need to improve studies of implementation and process evaluations, or the reporting of those studies. To improve the overall quality of process evaluations in this field, researchers should ensure that the publication of their results discusses and discloses ethical considerations, relationships with participants and policy recommendations, in addition to other critical elements that are more commonly included in study findings.

These may seem like disappointing findings but identifying the areas in which evidence is lacking is a crucial part of the Centre's work and, promisingly, these results do give us a clearer picture of where we should focus our research efforts – namely by evaluating the impact of financing, legislation and communication on the implementation of interventions. Furthermore, growth in evidence around education and skills and employment interventions present opportunities for systematic review.

The Centre has carried out a consultation exercise to identify priority evidence needs for which evidence is lacking, and then fill those gaps, either directly or indirectly. We are also working with key stakeholders to support us in undertaking rigorous evaluation of their programmes. We believe our contribution to building the evidence architecture for homelessness will help develop better strategies to tackle this complex social issue. When we update these maps again in a year’s time, we hope to see advances in these areas of research, as well as an increase in the UK’s evidence base across the board. We hope you’ll help us achieve those ambitions.

Useful links

Download the report

Explore the evidence and gap maps tool

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