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This project aims to assess the relative performance of various methods used for estimation of the size and prevalence of hidden (hard-to-reach) populations. We develop and describe the Bayesian model for the meta-analyses of the relative performance of methods. We describe the quantities of interest (inquiries) we can estimate both at the individual study level as well as at the meta-analysis level. Finally, we describe the “answer” strategies, i.e. how we estimate each quantity of interest both at the individual study level as well as at the meta-analysis level

In this presentation, we discuss the use of targeted advertisements on Facebook and Instagram to recruit refugees for online surveys. While the presentation also elaborates on our earlier research, it mainly draws from the Online Survey of Ukrainian Refugees (OSUR), conducted in the second half of April 2022 in Germany and Poland. Preliminary results of this survey are available in English (LSE Blog) and German (GESIS Blog). These slides were prepared for and used in a invited talk in the colloquium of the German Federal Office for Migration and Refugees’ research department held on July 25, 2022. While the talk was given in German, the slides were in English (with the exception of the title page)., {"references":["Pötzschke, S., Weiß, B., Hebel, A., Piepenburg, J. G., & Popek, O. (2022). Geflüchtete aus der Ukraine – Erste deskriptive Ergebnisse einer Onlinebefragung in Deutschland und Polen. GESIS - Leibniz-Institut für Sozialwissenschaften. https://www.doi.org/10.34879/gesisblog.2022.60","Pötzschke, S., Weiß, B., Hebel, A., Piepenburg, J. G., & Popek, O. (2022). Preliminary findings from an online survey of Ukrainian refugees in Germany and Poland. LSE Blog. https://blogs.lse.ac.uk/europpblog/2022/05/12/preliminary-findings-from-an-online-survey-of-ukrainian-refugees-in-germany-and-poland/"]}

Member countries of the Asia Pacific Malaria Elimination Network are pursuing the regional goal of malaria elimination by 2030. The countries are in different phases of malaria elimination, but most have demonstrated success in shrinking the malaria map in the region. However, continued transmission in hard‐to‐reach populations, including border and forest malaria, remains an important challenge. In this article, we review strategies for improving intervention coverage in hard‐to‐reach populations. Currently available preventive measures, including long‐lasting insecticidal nets and long‐lasting insecticidal hammocks, and prompt diagnosis and treatment need to be expanded to hard‐to‐reach populations. This can be done through mobile malaria clinics, village volunteer malaria workers and screening posts. Malaria surveillance in the hard‐to‐reach areas can be enhanced through tools such as spatial decision support systems. Policy changes by the malaria programs will be required for implementing the strategies outlined in this article. However, strategies or tools may be suitable for some population groups but difficult to implement in other groups.

Introduction Administering patient-reported outcome measures (PROMs) by text message may improve response rate in hard-to-reach populations. This study explored cultural acceptability of PROMs and compared measurement equivalence of the EQ-5D-3L administered on paper and by text message in a rural South African setting. Materials and methods Participants with upper or lower limb orthopaedic pathology were recruited. The EQ-5D was administered first on paper and then by text message after 24 h and 7 days. Differences in mean scores for paper and text message versions of the EQ-5D were evaluated. Test–retest reliability between text message versions was evaluated using Intraclass Correlation Coefficients (ICCs). Results 147 participants completed a paper EQ-5D. Response rates were 67% at 24 h and 58% at 7 days. There were no differences in means between paper and text message responses for the EQ-5D Index (p = 0.95) or EQ-5D VAS (p = 0.26). There was acceptable agreement between the paper and 24-h text message EQ-5D Index (0.84; 95% Confidence Interval (CI) 0.78–0.89) and EQ-5D VAS (0.73; 95% CI 0.64–0.82) and acceptable agreement between the 24-h and 7-day text message EQ-Index (0.72; CI 0.62–0.82) and EQ-VAS (0.72; CI 0.62–0.82). Non-responder traits were increasing age, Xhosa as first language and lower educational levels. Conclusions Text messaging is equivalent to paper-based measurement of EQ-5D in this setting and is thus a viable tool for responders. Non-responders had similar socioeconomic characteristics and attrition rates to traditional modes of administration. The EQ-5D by text message offers potential clinical and research uses in hard-to-reach populations.

The COVID-19 pandemic has further deepened socioeconomic and health inequities worldwide, especially among populations experiencing social vulnerability, such as international migrants. Sustained lockdowns and social distancing have raised challenges to conducting public health research with hard-to-reach populations. This study aims at exploring strategies to recruit “hard-to-reach” international migrants for qualitative public health research during the pandemic in Chile, based on the authors’ experience. A retrospective qualitative evaluation process was carried out on the recruitment processes of three qualitative research projects focused on international migrants in Chile. All projects were implemented during the COVID-19 pandemic, demanding complementary and flexible strategies: (i) social media; (ii) snowball sampling; (iii) referrals from social workers and pro-migrant and migrant-led organizations; (iv) vaccination centers and healthcare centers; and (v) community-based recruitment. The strategies are qualitatively evaluated around seven emerging qualitative categories: (i) feasibility during lockdown periods; (ii) speed of recruitment; (iii) geographical coverage; (iv) sample diversity; (v) proportion of successful interviews; (vi) ethical considerations; and (vii) cost. Engaging hard-to-reach international migrants in public health research during the pandemic required constantly adapting recruitment strategies. Furthermore, relying on strategies that were not only Internet-based promoted the participation of populations with limited access to the Internet and low-digital literacy.

Surveying people via the Internet presents both opportunities and challenges. The opportunities include quick access to respondents all over the world enabling fast realization of surveys at low costs. The challenges include a lack of control over both the sampling process and research implementation, as well as low response rates. This article describes a method of obtaining an appropriate sample of people for survey research utilising the power of the Internet, while simultaneously allowing the researcher to minimise risk thanks to enhanced control over the sampling process and the implementation of the survey. The proposed method could be used mainly in economic and social surveys; it allows researchers to reach selected groups of respondents and to conduct surveys on a global scale.•The proposed sampling method uses LinkedIn's network structure to quickly reach a dispersed population•Creating a list of units belonging to the study population resembles the snowball method, though the units are selected for the sample by the researcher and not indicated by the respondents., Graphical abstract Image, graphical abstract

Background: Web-based respondent-driven sampling is a novel sampling method for the recruitment of participants for generating population estimates, studying social network characteristics, and delivering health interventions. However, the application, barriers and facilitators, and recruitment performance of web-based respondent-driven sampling have not yet been systematically investigated. Objective: Our objectives were to provide an overview of published research using web-based respondent-driven sampling and to investigate factors related to the recruitment performance of web-based respondent-driven sampling. Methods: We conducted a scoping review on web-based respondent-driven sampling studies published between 2000 and 2019. We used the process evaluation of complex interventions framework to gain insights into how web-based respondent-driven sampling was implemented, what mechanisms of impact drove recruitment, what the role of context was in the study, and how these components together influenced the recruitment performance of web-based respondent-driven sampling. Results: We included 18 studies from 8 countries (high- and low-middle income countries), in which web-based respondent-driven sampling was used for making population estimates (n=12), studying social network characteristics (n=3), and delivering health-related interventions (n=3). Studies used web-based respondent-driven sampling to recruit between 19 and 3448 participants from a variety of target populations. Studies differed greatly in the number of seeds recruited, the proportion of successfully recruiting participants, the number of recruitment waves, the type of incentives offered to participants, and the duration of data collection. Studies that recruited relatively more seeds, through online platforms, and with less rigorous selection procedures reported relatively low percentages of successfully recruiting seeds. Studies that did not offer at least one guaranteed material incentive reported relatively fewer waves and lower percentages of successfully recruiting participants. The time of data collection was shortest in studies with university students. Conclusions: Web-based respondent-driven sampling can be successfully applied to recruit individuals for making population estimates, studying social network characteristics, and delivering health interventions. In general, seed and peer recruitment may be enhanced by rigorously selecting and motivating seeds, offering at least one guaranteed material incentive, and facilitating adequate recruitment options regarding the target population's online connectedness and communication behavior. Potential trade-offs should be taken into account when implementing web-based respondent-driven sampling, such as having less opportunities to implement rigorous seed selection procedures when recruiting many seeds, as well as issues around online rather than physical participation, such as the risk of cheaters participating repeatedly.

Background: The term ‘last mile’ has been used across disciplines to refer to populations who are farthest away, most difficult to reach, or last to benefit from a program or service. However, last mile research lacks a shared understanding around its conceptualization. Objectives: This project used a concept mapping process to answer the questions: what is last mile research in global health and, how can it be used to make positive change for health equity in the last mile? Methods: Between July and December 2019, a five-stage concept mapping exercise was undertaken using online concept mapping software and an in-person consensus meeting. The stages were: establishment of an expert group and focus prompt; idea generation; sorting and rating; initial analysis and final consensus meeting. Results: A group of 15 health researchers with experience working with populations in last mile contexts and who were based at the Matariki Network institutions of Queen’s University, CAN and Dartmouth College, USA took part. The resulting concept map had 64 unique idea statements and the process resulted in a map with five clusters. These included: (1) Last mile populations; (2) Research methods and approaches; (3) Structural and systemic factors; (4) Health system factors, and (5) Broader environmental factors. Central to the map were the ideas of equity, human rights, health systems, and contextual sensitivity. Conclusion: This is the first time ‘last mile research’ has been the focus of a formal concept mapping exercise. The resulting map showed consensus about who last mile populations are, how research should be undertaken in the last mile and why last mile health disparities exist. The map can be used to inform research training programs, however, repeating this process with researchers and members from different last mile populations would also add further insight.

Background Web-based respondent-driven sampling is a novel sampling method for the recruitment of participants for generating population estimates, studying social network characteristics, and delivering health interventions. However, the application, barriers and facilitators, and recruitment performance of web-based respondent-driven sampling have not yet been systematically investigated. Objective Our objectives were to provide an overview of published research using web-based respondent-driven sampling and to investigate factors related to the recruitment performance of web-based respondent-driven sampling. Methods We conducted a scoping review on web-based respondent-driven sampling studies published between 2000 and 2019. We used the process evaluation of complex interventions framework to gain insights into how web-based respondent-driven sampling was implemented, what mechanisms of impact drove recruitment, what the role of context was in the study, and how these components together influenced the recruitment performance of web-based respondent-driven sampling. Results We included 18 studies from 8 countries (high- and low-middle income countries), in which web-based respondent-driven sampling was used for making population estimates (n=12), studying social network characteristics (n=3), and delivering health-related interventions (n=3). Studies used web-based respondent-driven sampling to recruit between 19 and 3448 participants from a variety of target populations. Studies differed greatly in the number of seeds recruited, the proportion of successfully recruiting participants, the number of recruitment waves, the type of incentives offered to participants, and the duration of data collection. Studies that recruited relatively more seeds, through online platforms, and with less rigorous selection procedures reported relatively low percentages of successfully recruiting seeds. Studies that did not offer at least one guaranteed material incentive reported relatively fewer waves and lower percentages of successfully recruiting participants. The time of data collection was shortest in studies with university students. Conclusions Web-based respondent-driven sampling can be successfully applied to recruit individuals for making population estimates, studying social network characteristics, and delivering health interventions. In general, seed and peer recruitment may be enhanced by rigorously selecting and motivating seeds, offering at least one guaranteed material incentive, and facilitating adequate recruitment options regarding the target population’s online connectedness and communication behavior. Potential trade-offs should be taken into account when implementing web-based respondent-driven sampling, such as having less opportunities to implement rigorous seed selection procedures when recruiting many seeds, as well as issues around online rather than physical participation, such as the risk of cheaters participating repeatedly.

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. Background: Migrant populations are among the hardest to reach for research purposes. Methods: An interdisciplinary research team piloted a modified version of Boal's simultaneous dramaturgy with Roma mothers in Belfast. Results: The technique, based on scripted performances, translations, and discussions, proved effective for engaging with this hard-to-reach population, despite low levels of literacy, high language barriers, and cultural separateness. The approach uncovered attitudes to pregnancy which reinforce health inequalities, and present significant challenges for improving the health of marginalized populations. Conclusions: This pilot underlines the importance of building trust through holistic approaches to working with hard-to-reach populations through the creative arts.

Background We evaluated the effectiveness of different recruitment strategies used in a study aimed at eliminating/reducing second-hand smoke (SHS) exposure in Dutch children 0–13 years of age with a high risk of asthma. Methods The different strategies include: 1) questionnaires distributed via home addresses, physicians or schools of the children; 2) cohorts from other paediatric studies; 3) physicians working in the paediatric field (family physicians, paediatricians and Youth Health Care (YHC) physicians); and 4) advertisements in a local newsletter, at child-care facilities, and day-care centres. Results More than 42,782 families were approached to take part in the screening of which 3663 could be assessed for eligibility. Of these responders, 196 families met the inclusion criteria for the study. However, only 58 (one third) could be randomised in the trial, mainly because of no interest or time of the parents. The results showed that recruiting families who expose their children to SHS exposure is very challenging, which may be explained by lack of ‘recognition’ or awareness that SHS occurs in homes. The presence of asthma in the family, respiratory symptoms in the children, and even incentives did not increase parental motivation for participation in the study. Conclusions The recruitment process for an intervention program addressing SHS exposure in children was considerably more challenging and time consuming than anticipated. Barriers at both a parents level and a doctor’s level can be discriminated. Electronic supplementary material The online version of this article (10.1186/s12887-018-0983-4) contains supplementary material, which is available to authorized users.

Individuals, particularly those considered "hard-to-reach," often engage well with assessment tools that involve active dialogue and the co-construction of knowledge. Strengths profiling is one such tool that enables a person-centered and autonomy supportive approach to the identification of character strengths. Strength profiling is an adaptation of performance profiling used in sport psychology, which has not yet been utilized in broader psychological research or clinical practice. Supporting an individual by raising awareness of their personal character strengths is an effective and growing mechanism for promoting psychological well-being. Strengths profiling involves several stages of exploring, defining, and assessing character strengths, leading to the identification of signature strengths and goals for future development. Informed by personal construct theory, the present study explored the experiences of homeless young people living in sheltered accommodation (N = 116), when using strengths profiling at the start and end of a 10-week, strengths-based intervention. Mixed-method data was obtained from the strengths profiles, questionnaires measuring resilience, self-worth, and well-being, and diary entries. Findings revealed a rich array of character strength terminology and individual meanings. Participants found strengths profiling to be highly engaging, particularly due to their active role in strength identification, which prompted interesting and meaningful reflections on character strengths that were pertinent to them. Participants felt their signature strengths were vital protective factors within their lives and strengths profiles were correlated with resilience, self-worth, and well-being. Character strengths and resilience were also significantly and meaningfully improved pre/post-intervention, providing support for the use of strengths profiling as a tool for monitoring change in character strength perceptions. Overall, this study demonstrates the utility and versatility of strengths profiling as a new method in the discipline of positive psychology and strengths-based research and applied practice.

Background In response to a cholera outbreak among mobile, difficult-to-reach fishermen on Lake Chilwa, Malawi in 2016, a novel vaccine distribution strategy exploited the proven vaccine thermostability. Fishermen, while taking the first vaccine dose under supervision, received the second dose in a sealed bag, and were told to drink it two weeks later. This study assessed short-term vaccine protection of this strategy. Methods Patients with diarrhoea admitted to health facilities around lake were interviewed and a stool sample collected for PCR testing. Vaccine effectiveness was assessed in a case-control test-negative design by comparing cases (PCR-positive for V. cholerae O1) and controls (patients with diarrhoea but PCR-negative) and with the screening method that compared the proportions of vaccinated among cholera cases versus the general fishermen population. Results Of 145 study participants, 120 were fishermen living on the lake. Vaccine effectiveness at three-months was 90.0% [95% CI: 38.8; 98.4] among fishermen and 83.3% [95% CI: 20.8; 96.5] among all participants in the case-control test-negative design, and 97.5% [95% CI: 90.9; 99.3] with the screening method. Conclusion This strategy was effective in providing short-term protection in fishermen against cholera. Further research is needed to determine the adding value of the second dose and to identify the optimal vaccination strategies for different contexts.

Asynchronous Remote Communities (ARC) methodology has been used to explore HCI topics in a range of contexts. This innovative methodology takes advantage of the technological tools and platforms that are often the subject of HCI research to extend existing methods of data collection, pushing methodology beyond historical modes and allowing better connection with populations who have previously been left out of the research process. This SIG will make space for researchers and practitioners who are interested in using ARC methodology to connect with people who have already used ARC and discuss challenges and opportunities with this methodology, and how to extend similar kinds of innovative, distributed computing based methods into new contexts.

A number of factors common to the post-migration context have been shown to negatively impact the lives of new immigrants to Canada. Within the Arab community in Ashcroft, certain factors such as sponsorship requirements, intergenerational cohabitation practices, financial dependence, language barriers, and cultural stigmas often act as risk factors, increasing the vulnerability of older adults to abuse. Caroline Rochester has recently accepted the research coordinator position for the Elder Abuse Project at Rudyard University. The goal of the study is to identify the key factors that increase the risk of abuse of elders in the Arab community. Once these factors are better understood, it will be possible to develop culturally relevant strategies to address the risks that are amenable to change. Caroline’s team wants to collect qualitative data by organizing focus group interviews with community members; however, she is running into numerous difficulties conducting research with this hard-to-reach population. Mistrust of the research process and the absence of mutually beneficial relationships with the community have brought participant recruitment to a standstill. Moreover, the team’s failure to consider the cultural context of the population being studied has directly inhibited the progress of the project. It is clear that the current research methodology is not working and that a new approach is required. Caroline wonders what actions she should take to improve the research process. The goal of this case is to introduce readers to a number of commonly encountered concerns when conducting research with hard-to-reach and vulnerable populations. Through the development of solutions to the problems faced by the protagonist, readers will become more familiar with the principles of community-based participatory research and gain an understanding of the importance of cultural competence in research practice.

The use of lay health advisers has become an established approach within public health, in particular for impact on health inequalities and engaging socially excluded groups. Evidence on how differences in terms of the multiple role dimensions impact the outcomes of programs is limited. This creates ambiguity for decision makers on which roles should be implemented in different contexts for different needs. This paper applies realist logic to an inquiry to explore the mechanisms that may operate in lay-led intervention models and understand how, why, and in what respect these lead to particular outcomes. It draws on a project focusing on health-related lifestyle advisers and further insights gained from a subsequent related project about outreach with traveler communities. Analysis highlights multiple and potentially interacting aspects of lay health-adviser roles that may influence their success, including characteristics of lay health advisers, characteristics of target populations, purpose or intent of interventions, and how advice is given. A model is proposed from which to examine the contexts and mechanisms of lay health advisers that may impact outcomes, and is subsequently applied to two examples of reported lay health-adviser interventions. The combination of skills and characteristics of lay health advisers must be considered when planning which interventions might be appropriate when targeting specific needs or target populations. Focus only on the peer/layperson distinction may overlook other potentially important skills and mechanisms of action integral to lay health-adviser roles.

In recent years a relevant issue in the analysis of regional innovation policies supporting collaboration between firms and other organizations (e.g.: other firms, universities, research centres, etc.) is to evaluate the impact of such policies on the personal network of the targeted firms in a given region. To deal with this issue, it becomes of primary importance to have a reliable estimates of the size of innovation networks. In this work, we propose a novel use of capture-recapture approach to estimate the size and the composition of the personal networks of firms involved in regional innovation networks. Capturerecapture is a statistical method widely used to estimate the size of hidden population using two or more samples drawn from the population. The number of individuals observed in a sample and the number of those observed in both samples is used to estimate the number of those not selected in any sample. The method can be also used if two or more incomplete and overlapping lists of ascertained cases from different sources are available. We apply the proposed method on data from a survey conducted on a sample of 536 companies located in Friuli Venezia Giulia (a region in the north-east of Italy) who participated in the POR-FESR 2007-2013 call, named “Innovation, research, technology transfer and entrepreneurship”. The collaboration ties they claimed to entertain with other organizations (also not regionally bounded) before and after their participation to the call will be considered as the two lists on which the proposed capture-recapture approach is applied. The idea is to account for unobserved ties (and thus to estimate the network size of companies) using the number of ties observed only before or only after the participation to the call and the number of ties common to both.

Competing priorities between subsistence needs and health care may interfere with HIV health. Longitudinal data from the Los Angeles-based HIV Outreach Initiative were analyzed to examine the association between competing subsistence needs and indicators of poor retention-in-care among hard-to-reach people with HIV. Sacrificing basic needs for health care in the previous six months was associated with a 1.55 times greater incidence of missed appointments (95% CI 1.17, 2.05), 2.32 times greater incidence of emergency department visits (95% CI 1.39, 3.87), 3.66 times greater incidence of not receiving ART if CD4 < 350 (95% CI 1.60, 8.37), and 1.35 times greater incidence of detectable viral load (95% CI 1.07, 1.70) (all p < 0.01). Among hard-to-reach PLHIV, sacrificing basic needs for health care delineates a population with exceptional vulnerability to poor outcomes along the HIV treatment cascade. Efforts to identify and reduce competing needs for this population are crucial to HIV health outcomes.

Objective Report lessons learned in an RCT of Stop My Smoking (SMS) USA, a mHealth smoking cessation program for young adult smokers. Methods 164 18–24-year-olds were recruited nationally, online in 2011. Program evaluation data were provided at 12-week post-Quit Day. Results (1) Inviting participants to complete a brief text messaging survey and then asking them to complete a longer online survey resulted in the highest response rate (89%). (2) The positive tone of program messages was the most commonly noted program strength. (3) Suggested improvements included more social connectivity and additional assistance overcoming stressful situations. (4) Half of intervention participants moved through the program linearly and half went through various paths that reflected multiple relapses. Suggestions to use pharmacotherapy resulted in 22% of heavy smokers to utilize it. Conclusion Participant feedback provided concrete ways in which this and other young adult-focused interventions can improve messaging and program features to be even more salient. Practice implications Future young adult mHealth interventions could: Integrate models that are flexible to different “paths” of behavior change; address stressful life events directly and comprehensively; integrate proactive messaging that promotes pharmacotherapy options; and use text messaging as a gateway to longer online surveys.

Background Significant progress has been made in reducing the malaria burden in the Asia Pacific region, which is aggressively pursuing a 2030 regional elimination goal. Moving from malaria control to elimination requires National Malaria Control Programmes (NMCPs) to target interventions at populations at higher risk, who are often not reached by health services, highly mobile and difficult to test, treat, and track with routine measures, and if undiagnosed, can maintain parasite reservoirs and contribute to ongoing transmission. Methods A qualitative, free-text questionnaire was developed and disseminated among 17 of the 18 partner countries of the Asia Pacific Malaria Elimination Network (APMEN). Results All 14 countries that responded to the survey identified key populations at higher risk of malaria in their respective countries. Thirteen countries engage in the dissemination of malaria-related Information, Education, and Communication (IEC) materials. Eight countries engage in diagnostic screening, including of mobile and migrant workers, military staff, and/or overseas workers. Ten countries reported distributing or recommending the use of long-lasting insecticide-treated nets (LLINs) among populations at higher risk with fewer countries engaging in other prevention measures such as indoor residual spraying (IRS) (two countries), spatial repellents (four countries), chemoprophylaxis (five countries), and mass drug administration (MDA) (three countries). Though not specifically tailored to populations at higher risk, 11 countries reported using mass blood surveys as a surveillance tool and ten countries map case data. Most NMCPs lack a monitoring and evaluation structure. Conclusion Countries in the Asia Pacific have identified populations at higher risk and targeted interventions to these groups but there is limited information on the effectiveness of these interventions. Platforms like APMEN offer the opportunity for the sharing of protocols and lessons learned related to finding, targeting and successfully clearing malaria from populations at higher risk. The sharing of programme data across borders may further strengthen national and regional efforts to eliminate malaria. This exchange of real-life experience is invaluable to NMCPs when scarce scientific evidence on the topic exists to aid decision-making and can further support NMCPs to develop strategies that will deliver a malaria-free Asia Pacific by 2030.

Background: ‘Hard-to-reach’ is a term used to describe those sub-groups of the population that may be difficult to reach or involve in research or public health programmes. Application of a single term to call these sub-sections of populations implies a homogeneity within distinct groups, which does not necessarily exist. Different sampling techniques were introduced so far to recruit hard-to-reach populations. In this article, we have reviewed a range of ap¬proaches that have been used to widen participation in studies. Methods: We performed a Pubmed and Google search for relevant English language articles using the keywords and phrases: (hard-to-reach AND population* OR sampl*), (hidden AND population* OR sample*) and (“hard to reach” AND population* OR sample*) and a consul-tation of the retrieved articles’ bibliographies to extract empirical evidence from publications that discussed or examined the use of sampling techniques to recruit hidden or hard-to-reach populations in health studies. Results: Reviewing the literature has identified a range of techniques to recruit hard-to-reach populations, including snowball sampling, respondent-driven sampling (RDS), indigenous field worker sampling (IFWS), facility-based sampling (FBS), targeted sampling (TS), time-location (space) sampling (TLS), conventional cluster sampling (CCS) and capture re-capture sampling (CR). Conclusion: The degree of compliance with a study by a certain ‘hard-to-reach’ group de-pends on the characteristics of that group, recruitment technique used and the subject of inter-est. Irrespective of potential advantages or limitations of the recruitment techniques reviewed, their successful use depends mainly upon our knowledge about specific characteristics of the target populations. Thus in line with attempts to expand the current boundaries of our know-ledge about recruitment techniques in health studies and their applications in varying situa-tions, we should also focus on possibly all contributing factors which may have an impact on participation rate within a defined population group., Health Promotion Perspectives; ISSN: 2228-6497

Hepatitis C virus (HCV) is a public-health issue that drug users (DU) remain the major source of contamination in France. Conducting seroepidemiological surveys among this population to assess the HCV dynamic is difficult particularly due to their illicit practices. This population can be accessible through survey locations or can be hidden (who does not visit any location). To survey each part, we presented time-location sampling (TLS) and respondent-driven sampling. We presented TLS in the context of an indirect sampling and proposed a design-based inference taking into account the frequency of venue attendance (FVA) to estimate a total or a proportion. We recommend this method for estimating the prevalence of a disease in surveys among hard-to-reach populations, even if errors occur in the FVA reported by the participants. The ANRS-Coquelicot survey carried out in 2004 among DU attending centres providing services to drug users, then repeated in 2011, allowed us to estimate the HCV prevalence at 43.7%. Using these two surveys, we estimated age- and time-dependent HCV incidence from a mathematical model linking prevalence and incidence. This model consisted in combining a compartmental model with a regression model. The HCV incidence was thus estimated at 4.4/100 person-years in 2011. This method is an alternative approach to estimate incidence of a disease from cross-sectional epidemiological data in the absence of cohort or biological tests to identify acute infections. The decline in HCV incidence is to be expected given decreasing prevalence, recent developments in harm reduction measures and new therapeutic approaches despite a potential increase of at-risk behaviors., Le virus de l'hépatite C (VHC) est un problème majeur de santé publique dont les usagers de drogues (UD) constituent la principale source de contamination en France. Réaliser des enquêtes séro-épidémiologiques auprès de cette population pour suivre la dynamique du VHC s'avère difficile notamment en raison de leurs pratiques illicites. Cette population est en partie accessible par les lieux d'enquêtes et en partie "cachée" car ne fréquentant aucun lieu répertorié. Pour enquêter chaque partie, nous avons considéré l'échantillonnage lieux-moments (TLS) puis l'échantillonnage conduit par les répondants. Après avoir formalisé le TLS dans le cadre d'un sondage indirect, nous avons proposé un estimateur pour un total et une proportion, qui tient compte de la fréquentation multiple et hétérogène des lieux d'enquêtes. Nous recommandons cette méthode pour estimer la prévalence d'une maladie dans des études auprès de populations fréquentant des services, même en cas d'erreurs sur les fréquentations déclarées par les participants. L'enquête ANRS-Coquelicot réalisée en 2004 auprès des UD fréquentant des centres dédiés, puis répétée en 2011, a permis d'estimer la prévalence du VHC à 43,7%. A partir des deux enquêtes, nous avons ensuite estimé l'incidence du VHC par âge et en fonction du temps en construisant un modèle mathématique reposant sur la formulation d'une relation entre la prévalence et l'incidence. Ce modèle consistait en la combinaison d'un modèle compartimental et d'un modèle de régression. L'incidence du VHC a ainsi été estimée à 4,4/100 personnes-années en 2011. Cette approche est une alternative satisfaisante pour estimer l'incidence d'une maladie à partir d'enquêtes épidémiologiques transversales en l'absence de cohorte ou de tests biologiques permettant d'identifier les infections récentes. Compte tenu de la baisse de la prévalence, des mesures de réduction des risques et des avancées thérapeutiques, une diminution de l'incidence du VHC devrait se poursuivre malgré une potentielle augmentation des comportements à risque des UD.

Policy researchers face a range of pressures to incorporate the perspectives of ‘hard-to-reach’ groups in their research. In the specific case of public involvement policy in health (one example of the growing field of citizen participation initiatives in administrative contexts), researchers have struggled to accomplish this without compelling research participants to enter into a policy discourse that is unfamiliar and may be at odds with their self-understood roles as patients and citizens. This paper presents findings from an interpretive project which sought to understand the perspectives of young adults on local practices of public involvement in a socio-economically deprived area of Scotland. It recounts the researcher’s shifting standpoint in response to silences and absences within young adults’ reaction to the project, and argues that the everyday ‘tactics’ young adults described using in their interactions with health services be reimagined as relevant, albeit challenging forms of citizen participation.

The quest for integrated care has often been depicted as “crossing the boundaries”, going “beyond silos” or “cutting across” multiple systems, services, providers and settings. More recently, these health system and organization-centred concerns have been complemented with person-centred perspectives that focus on the needs of service users, their families and communities and what matters most for them. This new emphasis implies a new understanding of the scope of responsibilities of care systems: rather than waiting for people to attend the system to receive integrated care, it involves actively seeking those who might need it most and which are usually “hard-to-reach”. Person-centred approach urges systems and services to be more proactive and reach out to those vulnerable populations who are hard-to-reach. The chances of reaching these groups increase when organisations and services from all sectors align, coordinate their actions and work together. EFFICHRONIC: The EU-funded project EFFICHRONIC http://effichronic.eu/ aims to empower vulnerable hard-to-reach patients and caregivers to self-manage their chronic conditions. The project seeks to provide evidence on the positive return of investment and cost-efficiency of the application of the Chronic Disease Self-Management Programme (CDSMP) in different regions of 5 European countries (France, Italy, The Netherlands, Spain and UK) with a particular focus on the health-related, medical, social, cultural and economic factors linked with a higher burden of chronic disorders in Europe. Targeted Population: EFFICHRONIC aims at implementing the CDSMP in those groups of society that are most exposed to the negative effect of the social determinants of health. The EFFICHRONIC project uses the term “vulnerable” to refer to individuals that are not fully socially integrated and risk falling into social exclusion, either due to socio-economic hardship or due to physical or psychological reasons (the chronically ill, the disabled, the frail elderly or people suffering from mental health problems). A total sample of 2000 individuals receives the CDSMP programme. Acknowledgements: The project EFFICHRONIC has received funding from the European Union’s Health Programme (2014-2020) under Grant Agreement 738127. Workshop Programme Outline: We propose short presentations, followed by a half an hour discussion: EFFICHRONIC Overall Project approach: by Marta Pisano and An Boone (DG Public Health, Asturias Regional Government. Spain). 15 minutes The identification of vulnerable groups/individuals in the 5 countries through a multidimensional analysis and stratification methodology (Selfy-Multidimensional Prognostic Index): by Alberto Pilotto (Ente Galliera Hospital. Italy). 10 minutes Intersectoral strategies used to recruit vulnerable populations: by Yves-Marie Pers (Centre Hospitalier Universitaire Montpellier. France).Preliminary results after a year and a half into the EFFICHRONIC project. 10 minutes Project Evaluation framework: Siok-Swan Tan (Erasmus University Medical Centre. The Netherlands). A rigorous methodology, involving 5 different settings will provide evidence on the impact of EFFICHRONIC. 10 minutes Methodology of Internal Quality control: by Barbara Branchini (Polibienestar Research Institute. Spain). 10 minutes Communication and Dissemination: by Graham Edward Baker (Quality Institute for Self-management education and training. UK). 10 minutes Policy recommendations and guidelines to scale up the most effective outreach strategies to other settings in Europe: by Arturo Alvarez. 10 minutes

The use of personal names for screening is an increasingly popular sampling technique for migrant populations. Although this is often an effective sampling procedure, very little is known about the properties of this method. Based on a large German survey, this article compares characteristics of respondents whose names have been correctly classified as belonging to a migrant population with respondentswho aremigrants and whose names have not been classified as belonging to a migrant population. Although significant differences were found for some variables even with some large effect sizes, the overall bias introduced by name-based sampling (NBS) is small as long as procedures with small false-negative rates are employed.

For studies using respondent driven sampling (RDS), the current practice of collecting a sample twice as large as that used in simple random sampling (SRS) (i.e. design effect of 2.00) may not be sufficient. This paper provides empirical evidence of sample-to-sample variability in design effects using data from nine studies in six countries among injecting drug users, female sex workers, men who have sex with men and male-to-female transgender (MTF) persons. We computed the design effect as the variance under RDS divided by the variance under SRS for a broad range of demographic and behavioral variables in each study. We also estimated several measures for each variable in each study that we hypothesized might be related to design effect: the number of waves needed for equilibrium, homophily, and mean network size. Design effects for all studies ranged from 1.20 to 5.90. Mean design effects among all studies ranged from 1.50 to 3.70. A particularly high design effect was found for employment status (design effect of 5.90) of MTF in Peru. This may be explained by a "bottleneck"--defined as the occurrence of a relatively small number of recruitment ties between two groups in the population. A design effect of two for RDS studies may not be sufficient. Since the mean design effect across all studies was 2.33, an effect slightly above 2.00 may be adequate; however, an effect closer to 3.00 or 4.00 might be more appropriate.

The sampling frame in most social science surveys excludes members of certain groups, known as hard-to-reach groups. These groups, or subpopulations, may be difficult to access (the homeless, e.g.), camouflaged by stigma (individuals with HIV/AIDS), or both (commercial sex workers). Even basic demographic information about these groups is typically unknown, especially in many developing nations. We present statistical models which leverage social network structure to estimate demographic characteristics of these subpopulations using Aggregated relational data (ARD), or questions of the form "How many X's do you know?" Unlike other network-based techniques for reaching these groups, ARD require no special sampling strategy and are easily incorporated into standard surveys. ARD also do not require respondents to reveal their own group membership. We propose a Bayesian hierarchical model for estimating the demographic characteristics of hard-to-reach groups, or latent demographic profiles, using ARD. We propose two estimation techniques. First, we propose a Markov-chain Monte Carlo algorithm for existing data or cases where the full posterior distribution is of interest. For cases when new data can be collected, we propose guidelines and, based on these guidelines, propose a simple estimate motivated by a missing data approach. Using data from McCarty et al. [Human Organization 60 (2001) 28-39], we estimate the age and gender profiles of six hard-to-reach groups, such as individuals who have HIV, women who were raped, and homeless persons. We also evaluate our simple estimates using simulation studies., Published in at http://dx.doi.org/10.1214/12-AOAS569 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org)

This paper aims to describe the sample design and the survey plan used in the survey on incoming tourism in Sicily and Sardinia. The specific goals of the survey are related: a) to the measurement and the analysis of un-observed tourism; b) to the evaluation of tourist mobility within the two Islands; c) to the analysis of some key-factors related to the holyday experience of tourists. It is well known that regional tourists are very difficult-to-reach populations and the problems in sampling human mobile populations derive from the absence of a list of units component units (frame). Despite these issues are well-known in literature under the broader categories of hard to reach, or hidden, or mobile populations, etc., the methodological solutions and most of all the empirical applications in tourism studies are almost poor. The sampling strategy undertaken to analyze non resident tourists leaving Sicily and Sardinia at the end of their vacation is a complex, multi-stage, stratified Time-Location Sampling (TLS). Under this perspective, the availability of information on the distribution of tourism flows by time (months) and space (departure places) for the two Islands was a fundamental prerequisite for the implementation of the sample design. Key words: Hard-to-reach populations; mobile populations; time-location sampling; time-space sampling; frontier surveys, border surveys. Parole chiave: Popolazioni mobili; campionamento spazio-temporale; indagini campionarie alle frontiere.

This article proposes and applies a method to estimate the revenues of beggars in Brussels (Belgium). This is relevant for three reasons. First, though the literature on the informal economy assumes that the income will be low, we lack reliable empirical knowledge of informal street-level activities like begging, in particular due to the prevalence of many irregular Eastern-European immigrants among the begging population. Second, popular representation of beggars often depicts them as fraudulent, criminal and wealthy. Finally, the assumption of criminal organizations behind beggars legitimated the recent criminalization of (aspects of) begging in Western countries, e.g. in Belgium and France. An analysis of existing attempts to measure beggars’ income teaches us that the best design is to triangulate with data from different sources. Three datasets were collected, based on observation, self-reports and quasi-experimental observations. The combination of these datasets allows for more reliable and valid conclusions. The hypotheses based upon popular myths and the assumptions behind the criminalization of begging are dismissed. The evidence does seem to support the hypothesis based upon the literature on informal activities.

As part of a large sexual health study, we used two different approaches to target Sexual Minority Individuals (SMIs). Firstly, we drew on a probability sample (1,832 respondents aged 14-80) of the Flemish population in Belgium. Secondly, we set up a targeted sampling design followed by an Internet survey. Our focus was to explore how two different sampling procedures and survey designs could lead to differences in sample characteristics. Results showed that for female SMIs (we excluded male SMIs from the analyses due to their low numbers) the population sample differed from the Internet sample in terms of sociodemographic characteristics (the latter included younger and more highly educated respondents) and scores on sexual orientation dimensions (the population sample included more respondents who didn’t identify as lesbian or bisexual but reported same-sex sexual experiences and desire). Respondents’ scores on sexual health indicators differed between the samples for two of the seven variables. We discuss implications for improving the quality and validity of nonrandom samples.