Understanding

Rapid Re-housing:

What Did We Learn?

U.S. Department of Housing and Urban Development | Office of Policy Development and Research

DISCLAIMER

The contents of this report are the views of the contractor and do not necessarily reflect the views or policies of the U.S. Department of Housing and Urban Development or the U.S. Government.

Understanding Rapid Re-housing:

What Did We Learn?

Prepared by:

Jill Khadduri

Lauren Dunton

Scott Brown

Abt Associates

September 2020

Acknowledgments

This synthesis of findings of the Understanding Rapid Re-housing Study relies on the work of a large study team and several reports. We thank our colleague Michelle Wood for comments on a draft of this paper and Mindy Ault of HUD’s Office of Policy Development and Research for her guidance throughout the study.

Foreword

As homelessness remains a major concern in our communities, practitioners and homeless services providers as well as researchers and academics are in search of stronger evidence regarding the relative effectiveness of interventions that assist households to exit homelessness and obtain stable housing. One of the fastest-growing approaches to moving people out of homelessness is rapid re-housing (RRH), a program model that provides temporary assistance to people experiencing homelessness, to move them quickly into permanent housing and allow them to stabilize there. 1

The Understanding Rapid Re-housing study is a four-year project with five reports plus a data repository representing the first comprehensive documentation of RRH programs nationwide.

The reports include a review of RRH outcomes literature; a supplemental analysis of data from the Family Options Study about differences in the use of RRH in the study communities; a report using data from surveys administered to Continuums of Care and RRH programs along with interviews with 20 RRH programs to describe features and program models; a report that describes findings from in-depth interviews with 30 RRH participants in two communities at different stages of RRH; and finally, a report which presents findings from 16 months of qualitative research with 16 households in two communities during and after their time in RRH.

RRH is not a one-size-fits-all strategy—it has proven to be an effective way for some households to stabilize in permanent housing, but less so for others. Like any solution to a complicated problem, RRH has strengths and weaknesses. This synthesis brief summarizes the findings from the different components of this study in a way that addresses the major questions surrounding the rapid re-housing program and its efficacy for individuals and families experiencing homelessness. It also highlights areas where further study is warranted.

Todd Richardson

General Deputy Assistant Secretary for Policy Development and Research U.S. Department of Housing and Urban Development

1 National Alliance to End Homelessness, 2014. Core Components of Rapid Re-housing: Fact Sheet.

https://endhomelessness.org/ending-homelessness/solutions/rapid-re-housing/

Understanding Rapid Re-Housing: What Did We Learn?

Background

By 2010, evidence from the early implementation of rapid re-housing (RRH) in a few communities showed that the model held promise for resolving homelessness (Walton et al., 2018; Gubits et al., 2018).

Spurred by a growing view that homelessness is largely a housing problem and that people experiencing homelessness do not need a transitional stage of intensive services before returning to housing, 2 RRH was first implemented in 2009 and provided a temporary rent subsidy with case management focused on helping people afford housing on their own when the rent subsidy ended. The Homelessness Prevention and Rapid Re-housing Program (HPRP) included in the stimulus package enacted early in 2009 provided substantial funding for RRH, and RRH became a major component of both federal and local strategies for addressing homelessness (Gubits et al., 2018; Shinn and Khadduri, 2020). 3 Additional funding for RRH, limited to veterans, followed in the Supportive Services for Veteran Families (SSVF) program. SSVF

started with a pilot in 2012 and then became a major part of the homeless services system (Gubits et al., 2018).

Unlike traditional federal housing subsidies, RRH does not follow a uniform approach for establishing the rental subsidy. RRH programs adopt varying policies for determining the amount of rent subsidy a household receives: if and how the subsidy is tied to the household’s income, if and how it is tied to a housing unit’s rent, and how the assistance varies over time. Communities receiving HPRP funding were permitted to design their own systems within the general constraint that assistance would in no case last longer than 18 months. The duration of assistance typically was shorter than that (Gubits et al., 2018; Walton et al., 2018). 4

In 2010, RRH (then referred to as community-based rapid re-housing or CBRR) was added as a treatment arm to the randomized controlled study known as the Family Options Study to examine the effectiveness of this new approach compared with leaving people to find their way out of shelter (usual care), project-based transitional housing (PBTH), 5 and a long-term housing subsidy (SUB, usually a Housing Choice Voucher). Families with children who had been in emergency shelters for at least seven days were randomized into the treatment arms between September 2010 and January 2012. Findings from the Family Options Study emerged in three stages: descriptive information from the set-up of the study, impacts at 20 months, and impacts at 3 years (Gubits et al., 2013; 2015; 2016).

Understanding Rapid Re-housing Study

Many policymakers and practitioners considered the Family Options Study findings interesting but not definitive. The findings reflected the programs in only 12 communities and early in their implementation.

The study also examined only families with children, providing no evidence about effects of RRH on 2This view is sometimes applied generally as “housing first,” although that term first was used for a particular model of housing with permanent subsidies and access to intensive but voluntary services.

3Shortly before that, Congress had funded a Rapid Re-housing Demonstration program, and the demonstration was implemented at the same time as HPRP.

4Later extended to 24 months for HUD-funded programs. RRH programs funded by the Veterans Administration are limited to 12 months.

5Transitional housing sometimes uses a model that provides rent subsidies in scattered-site units. The Family Options Study randomized families only to project-based transitional housing in order to create a clear distinction between transitional housing and rapid re-housing, both of which are temporary.

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Understanding Rapid Re-Housing: What Did We Learn?

people experiencing homelessness as individuals. In the years following the Family Options Study, federal guidance regarding RRH programs changed, community practice matured, and SSVF provided RRH assistance to many households without children. In view of the widespread and increasing use of RRH and the further evolution of the concept, HUD commissioned additional research, the Understanding Rapid Re-housing Study. Understanding Rapid Re-housing is not another experiment. Rather, it uses various approaches to learn more about how RRH was being used at a later point in time and over a larger number of different communities:

• A review of outcomes measured as of 2018 by performance measurement systems as well as by research studies. The report on this study component is Gubits et al., 2018.

• Further, but non-experimental, analysis of Family Options Study data, providing more detail on how families in the study used RRH. The report on this study component is Walton et al., 2018.

• A web survey of all Continuums of Care (CoCs) and all RRH programs in operation as of 2018 to learn more about program features and experience from a large number of communities at a later point in time than the Family Options Study. The web survey was supplemented by interviews with program directors or managers of 20 RRH programs. The report on this study component is Dunton and Brown, 2019.

• Intensive interviews with 30 RRH program participants in two communities, followed by ethnographic research with 16 of those individuals and families over a 15-month period, from late 2018 through early 2020. The reports on this study component are Jefferson et al., 2019 and 2020.

Taken together, the findings from these components of the Understanding Rapid Re-housing Study shed light on several questions:

• Who do RRH programs serve?

• What are the predominant RRH program models?

• What influences local choices of program models?

• How does participation in RRH fit into a longer trajectory of the experience of families and individuals with housing instability?

• What outcomes can be expected from RRH? Rapid exit from homelessness? Stabilization in the household’s own housing? Longer-term housing stability?

• What do we still not know about RRH? What further research is needed?

Who do Rapid Re-housing programs serve?

Originally conceived mainly as a tool for helping families leave homelessness, RRH now serves people experiencing homelessness both as families and as individuals. The SSVF program serves mainly veterans experiencing homelessness on their own, and only about one-fifth of RRH programs (regardless of funding source) require a participant to have a child under the age of 18 present in the household (Dunton and Brown, 2019). Most programs reported that they did not focus exclusively either on individuals or on families. Twelve of the 16 households the research team recruited into the ethnographic study were adults experiencing homeless on their own.

What are the predominant RRH program models?

As of 2018, 93 percent of RRH programs reported that they were part of the coordinated entry system (CES) through which people experiencing a housing crisis in a community seek assistance and are 2

Understanding Rapid Re-Housing: What Did We Learn?

prioritized and referred to programs. Four of five programs said that the CES makes program referrals, and 69 percent that the CES assesses appropriateness for RRH. Many CES use the Vulnerability Index Service Assessment Tool (VI-SPDAT) to generate by-name lists of households to be referred to RRH

when a program slot becomes available (Dunton and Brown, 2019). By 2018, this practice appears to have resulted in a very different set of households admitted to RRH programs than was found by the Family Options Study. The VI-SPDAT focuses on psychosocial barriers rather than on the ability to become self-sufficient over a relatively short period of time. The programs from which the participants in the ethnographic research were recruited were prioritizing high-barrier households (Jefferson et al., 2019).

Findings from the Family Options Study on RRH are:

• Transitional housing was no more effective than RRH in preventing returns to homelessness or improving family well-being in other domains (Gubits et al., 2015; 2016). This finding validated HUD’s and many communities’ choices to emphasize RRH over transitional housing in their use of federal and local funding that could be applied to either model.

• A long-term rent subsidy was much more effective than RRH in almost all respects in promoting housing stability. SUB prevented returns to homelessness compared with UC, whereas CBRR did not. SUB had radiating effects on various dimensions of the well-being of adults and children, whereas CBRR did not (Gubits et al., 2015; 2016).

• As of 20 months following random assignment, RRH had a modest advantage over a long-term housing subsidy in encouraging work effort. This result may have been because of employment-related services that were part of RRH case management, but it is more likely that it reflected the slight work-discouraging effect of a long-term and deep housing subsidy. This difference between CBRR and SUB had faded three years after random assignment (Gubits et al., 2015; 2016).

• RRH shortened shelter stays by about half a month compared with UC and showed a cost savings of about nine percent compared with leaving families to find their way out of shelter. This finding provided some support for one of the key objectives of RRH (Gubits et al., 2015; 2016).

• As implemented at the time of the study in the 12 study communities, RRH screened out the families with the greatest economic and psychosocial challenges.* The design of the Family Options Study ensured that this screening did not bias the estimates of CBRR’s impact—only families eligible for CBRR and randomized to other treatment arms were compared to CBRR. The extensive screening by RRH programs became apparent during the implementation of the Family Options Study (Gubits et al., 2013), and in 2012, HUD issued guidance discouraging such screening.

• In open-ended, qualitative interviews, many families expressed negative reactions to aspects of the RRH

program model—notably, uncertainty about how much help they would receive with the rent and for how long, the case manager’s role in making that determination, and how their own behavior would affect those decisions (Gubits et al., 2013; Fischer et al., 2014).

*Additional detail on screening by each of the study communities is described in Walton et al., 2018.

Responses to a series of web survey questions on program models show much variety in how RRH

programs are structured and, in particular, how they use rent subsidies to place people experiencing 3

Understanding Rapid Re-Housing: What Did We Learn?

homelessness into housing. A cluster analysis6 based on 12 program features reveals three distinct RRH

types:

• One-time assistance—for example, security deposits and other move-in assistance—but no ongoing rent subsidy. This model is used by 12 percent of programs and by programs that serve a somewhat larger number of households annually, compared with the other models.

• Ongoing rent subsidies that decline (taper down) over time—paying the full rent or subsidy for an initial period and then reducing the amount of assistance over a subsequent period. Tapering could mean reducing the percentage of the rent paid over time or varying the elements of a “housing gap”

formula (rent minus a percentage of income). 7 This model is used by 35 percent of programs.

• Ongoing rent subsidies that remain fixed (do not taper down) over time—for example, continuing to pay a fixed percentage of the rent or continuing to use a traditional “housing gap” formula (rent minus a percentage of household income) with components that change over time only if actual rent or actual income change. This model is used by 53 percent of programs.

The approach to case management did not vary greatly among program types. Programs with one-time assistance are somewhat more likely than the other models to vary the intensity of case management according to need after a participant moves into a housing unit. Programs with ongoing rent subsidies that decline are slightly more likely than those that do not decline to require participation in case management after move-in and to require case management more frequently than once a month.

From the standpoint of program participants, case management is an important part of the RRH program.

Although case managers make referrals to employment and other services and connect people with benefits for which they are eligible, life coaching and emotional support are the case manager roles participants appear to value most. In the qualitative research, some participants expressed concerns about ambiguity about the duration of assistance and how it would change over time (Jefferson et al., 2020).

What influences the local choice of program models?

The source of the funding for the RRH program is important. Programs funded by SSVF are more likely than programs using HUD funding to provide only move-in or security deposit assistance to the average household served or to pay the full rent for a short period of time. The cluster analysis confirms that RRH

programs that provide only one-time assistance are more likely to have SSVF funding and less likely to have HUD CoC funding than programs that provide ongoing assistance. 8 All three program models were similarly likely to have funding from HUD’s Emergency Solutions Grant program.

6The program features are responses to survey questions about what the average or typical participant receives and were chosen because they vary sufficiently to differentiate programs. The study team used an agglomerative hierarchical clustering algorithm to examine how RRH programs surveyed cluster together based on their similarities across a range of weighted attributes. This analysis builds on the less formal identification of program types in Dunton and Brown (2019), which also found three predominant models, but with somewhat different attributes: one-time financial assistance, short-term intensive assistance, and longer-term partial or tapered assistance. This more rigorous analysis finds that whether the subsidy tapers down over time or remains the same over time better distinguishes program clusters than the duration of the assistance. Scott Brown and Jason Rodriguez conducted the analysis, which is available on request.

7For example, reducing over time the maximum rent that can be subsidized or requiring the household to pay an increasing percentage of income.

8 Few programs reported receiving both HUD and VA funding (7 to 9 percent across program models).

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Understanding Rapid Re-Housing: What Did We Learn?

Programs that provide ongoing rent subsidies, either tapered or fixed over time, are more often funded by HUD. Although HUD-funded programs use a variety of subsidy approaches, they are more likely than programs funded by SSVF to use a traditional “housing gap” formula—that is, total current rent minus a percentage of income (Dunton and Brown, 2019).

Housing market conditions are also important. Somewhat surprisingly, programs in high-cost, tight markets are likely to provide proportionally less rental assistance than programs in lower-cost, looser markets. Almost one-half of programs in these markets use a tapered assistance model, and the provision of only one-time assistance is also slightly more common in these markets. This may be because of the larger numbers of people experiencing homelessness in high-cost, tight markets. With more people needing help leaving homelessness, CoCs and RRH programs choose to provide less assistance to each household so that they can serve more households (Dunton and Brown, 2019). Programs that do not phase down the rent subsidy are more typical of smaller programs in lower-cost, looser markets.

How does participation in RRH fit into a longer trajectory of housing instability?

As of 2018–2019, RRH was often serving people with histories of housing instability, sometimes dating back to homelessness and frequent moving during their childhoods. Some people had been stably housed and employed until a life event such as loss of housing provided by a relative, an injury preventing work, or a crisis related to substance abuse changed their life course (Jefferson et al., 2019). Often the underlying issues correlated with poverty—insecure employment, health issues, involvement with the criminal justice system—persisted during and after participation in RRH. For those potentially able to work, employment was still unstable, and transportation and child care often were barriers to working.

Some people fell back into substance abuse, and some had jail stays. Returning to homelessness was not uncommon (Jefferson et al., 2020).

What outcomes can be expected from RRH?

Rapid exit from homelessness. Not all exits from homelessness aided by RRH are rapid, but the program as currently designed should be able to attain this objective. In the Family Options Study, the median time between random assignment to RRH and the start of assistance was two months, and some communities provided assistance within one month (Walton et al., 2018). A non-experimental study of the RRH

program funded by the Veterans Administration showed an average length of time from program enrollment to a housing placement of 45 days, with one-third of participants obtaining housing within 2

weeks (Gubits et al. 2018).

The study’s web survey asked RRH programs for the average length of time between a household entering a shelter or otherwise identified as homeless and the household engaging with the RRH

program. 9 The RRH programs reported that a majority of households served (57 percent) are engaged within 2 weeks. The survey also asked about the time between engagement and move-in to a permanent housing unit. More than two-thirds of programs (71 percent), serving almost two-thirds of households (61

percent), reported that it takes less than 6 weeks between engagement and move-in. Taken together, about one-fifth of households served by RRH (21 percent) are engaged quickly (in less than 2 weeks) and 9 These findings about time to exit from homelessness are based on new analysis and were not reported in Dunton and Brown (2019).

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Understanding Rapid Re-Housing: What Did We Learn?

subsequently move into a permanent housing placement within less than 1 month. Another 24 percent of households are engaged quickly and then are housed within another 4 to 8 weeks.

The elapsed time between entry into homelessness and engagement by an RRH program does not vary much across housing markets. Not surprisingly, however, it takes longer to place a household in permanent housing in high-cost, tight rental markets. The majority of households served by RRH in high-cost, tight markets (57 percent) take 8 weeks or more from engagement to move-in. In low-cost, loose markets, more than two-fifths of households move in within one month of engagement by an RRH

program, and just under half take more than one month but less than two.

Placement into a regular housing unit in the community, giving the family or individual a chance to

become more economically stable through employment or access to benefits. Most of the evidence on RRH shows high placement rates into permanent housing. The most extensive data are from performance reports on the RRH funded by HPRP and from the Veterans Administration’s SSVF program, showing placement rates of 82 to 84 percent (HPRP) and 70 to 79 percent (SSVF) (Gubits et al., 2018). Following placement into housing, some households may become economically stable. Links to employment services appear to have little value, however, even when apparently following current best practices.

Barriers to work are simply too extensive (Jefferson et al., 2020). For those with behavioral health challenges, including severe mental illness and substance use disorders, RRH as currently implemented does not appear to focus sufficiently on access to specialized services (Jefferson et al., 2020). Families with several children appear to have a more difficult time maintaining housing stability (Walton et al., 2018) and working (Jefferson et al., 2020).

Avoiding returns to homelessness. Many people have single episodes of homelessness and, despite ongoing challenges, do not become homeless again (Walton et al., 2018). Performance measurement of the SSVF program shows a one-year return rate of 16 percent for individuals and 9 percent for families (Gubits et al., 2018). The National Alliance to End Homelessness has set a performance benchmark of no more than 15 percent returns to homelessness within a year, which should be within the reach of RRH

programs (Gubits et al., 2018).

For those who face another housing crisis that will tip them into homelessness, however, nothing in the Understanding Rapid Re-housing Study challenges the finding of the Family Options Study that a rent subsidy needs to provide enough assistance to make housing affordable and needs to last more than a few months in order to be effective at preventing returns to homelessness. A large number of those followed by the ethnographic work that was part of the Understanding Rapid Re-housing Study were homeless again or in precarious housing situations at the end of the observation period.

What do we still not know about RRH?

The Understanding Rapid Re-housing study provides answers or at least insights into many key questions about the RRH program model as implemented as of 2018, but we still need to learn more to make a temporary rent subsidy combined with case management an effective approach for ending homelessness.

What we learned from the Understanding Rapid Re-housing study suggests the following areas for future research.

How long should a temporary rent subsidy last? How deep should it be? How important is predictability for helping the family or individual served achieve stability? The Research Council of the National Alliance to End Homelessness has recommended randomized controlled trials to compare some explicit program models rather than the array of programs implemented under the RRH umbrella (NAEH, 2020).

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Understanding Rapid Re-Housing: What Did We Learn?

The program typology developed by the Understanding Rapid Re-housing Study would be useful for helping to define those models.

What benefits and services should be the focus of RRH case management? It should be possible to gain preliminary evidence on this question by testing the feasibility and outcomes of programs with emphases suggested by the Understanding Rapid Re-housing Study—for example, a model that emphasizes childcare and transportation assistance rather than employment services or a model that addresses substance abuse more directly and proactively than current RRH programs do.

Who should RRH serve? The extensive screening to find families most likely to gain income and afford housing on their own that was prevalent at the time of the Family Options Study clearly was not the right choice, but perhaps neither is using a tool to prioritize those with the greatest psychosocial challenges. It might be possible to use RRH and HMIS administrative data to relate outcomes to factors used by assessment tools. An important first step is to evaluate the VI-SPDAT, the current assessment tool that is widely used but has never been validated (NAEH, 2020).

References

Dunton, Lauren, and Scott R. Brown. 2019. Rapid Re-housing in 2018: Program Features and Assistance Models. Report prepared by Abt Associates for the U.S. Department of Housing and Urban Development, Office of Policy Development and Research. Washington, DC: Government Printing Office.

https://www.huduser.gov/portal/Understanding-rapid-re-housing-study.html.

Fisher, Benjamin W., Lindsay S. Mayberry, Marybeth Shinn, and Jill Khadduri. 2014. “Leaving Homelessness Behind: Housing Decisions Among Families Exiting Shelter,” Housing Policy Debate, 24(2): 364-386.

Gubits, Daniel, Korrin Bishop, Lauren Dunton, Michelle Wood, Tom Albanese, Brooke Spellman, and Jill Khadduri. 2018. Understanding Rapid Re-housing: Systematic Review of Rapid Re-housing Outcomes Literature. Report prepared by Abt Associates for the U.S. Department of Housing and Urban Development. Washington, DC: Government Printing Office.

https://www.huduser.gov/portal/Understanding-rapid-re-housing-study.html.

Gubits, Daniel, Brooke Spellman, Lauren Dunton, Scott Brown, and Michelle Wood. 2013. Interim Report: Family Options Study. Report prepared by Abt Associates. Washington, DC: Government Printing Office, U.S. Department of Housing and Urban Development.

https://www.huduser.gov/publications/pdf/HUD_503_Family_Options_Study_Interim_Report_v2.pdf.

Gubits, Daniel, Marybeth Shinn, Stephen Bell, Michelle Wood, Samuel Dastrup, Claudia D. Solari, Scott R. Brown, Steven Brown, Lauren Dunton, Winston Lin, Debi McInnis, Jason Rodriguez, Galen Savidge, and Brooke E. Spellman. 2015. Family Options Study: Short-Term Impacts of Housing and Services Interventions for Homeless Families. Report prepared by Abt Associates. Washington, DC: Government Printing Office, U.S. Department of Housing and Urban Development.

http://www.huduser.gov/portal/portal/sites/default/files/pdf/FamilyOptionsStudy_final.pdf.

Gubits, Daniel, Marybeth Shinn, Michelle Wood, Stephen Bell, Samuel Dastrup, Claudia D. Solari, Debi McInnis, Tom McCall, and Utsav Kattel. 2016. Family Options Study: Three-Year Impacts of Housing and Services Interventions for Homeless Families. Report prepared by Abt Associates. Washington, DC: Government Printing Office, U.S. Department of Housing and Urban Development.

https://www.huduser.gov/portal/sites/default/files/pdf/Family-Options-Study-Full-Report.pdf.

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Understanding Rapid Re-Housing: What Did We Learn?

Jefferson, Anna, Lauren Dunton, Hannah Thomas, Anna Mahathey, and Jill Khadduri. Forthcoming.

Understanding Rapid Re-housing through Participants’ Experiences. Report prepared by Abt Associates for the U.S. Department of Housing and Urban Development, Office of Policy Development and Research.

Jefferson, Anna, Hannah Thomas, Jill Khadduri, Anna Mahathey, and Lauren Dunton. 2019. Findings from Initial Interviews with Rapid Re-housing Participants. Report prepared by Abt Associates for the U.S. Department of Housing and Urban Development, Office of Policy Development and Research.

https://www.huduser.gov/portal/publications/RRH-interviews-report.html.

National Alliance to End Homelessness. 2020. Homelessness Research Institute, A Research Agenda for Ending Homelessness. Washington, DC: National Alliance to End Homelessness.

Shinn, Marybeth, and Jill Khadduri. 2020. In the Midst of Plenty: How to Prevent and End Homelessness in the United States. Hoboken, NJ: Wiley-Blackwell, Wiley Contemporary Social Issues Series.

Walton, Douglas, Michelle Wood, Jason Rodriguez, Jill Khadduri, Daniel Gubits, Lauren Dunton, and Marybeth Shinn. 2018. Understanding Rapid Re-housing: Supplemental Analysis of Data from the Family Options Study. Report prepared by Abt Associates for U.S. Department of Housing and Urban Development, Office of Policy Development and Research. Washington, DC: Government Printing Office. https://www.huduser.gov/portal/Understanding-rapid-re-housing-study.html.

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U.S. Department of Housing and Urban Development Offce of Policy Development and Research

Washington, DC 20410-6000

July 2021

Document Outline

Understanding Rapid Re-housing: What Did We Learn?

Acknowledgments

Foreword

Background

Understanding Rapid Re-housing Study

Who do Rapid Re-housing programs serve?

What are the predominant RRH program models?

Findings from the Family Options Study on RRH are:

What influences the local choice of program models?

How does participation in RRH fit into a longer trajectory of housing instability?

What outcomes can be expected from RRH?

What do we still not know about RRH?

References

Table of Contents

Understanding Rapid Re-housing: What Did We Learn?

Acknowledgments

Foreword

Background

Understanding Rapid Re-housing Study

Who do Rapid Re-housing programs serve?

What are the predominant RRH program models?

Findings from the Family Options Study on RRH are:

What influences the local choice of program models?

How does participation in RRH fit into a longer trajectory of housing instability?

What outcomes can be expected from RRH?

What do we still not know about RRH?

References