Special issue: Probability and Nonprobability Sampling: Sampling of hard-to-reach survey populations
With the following collection of articles, Survey Methods: Insights from the Field’ aims to give an overview about the current state of the hard-to-reach research and the ongoing dispute between the two above mentioned sampling methods. Moreover, this Special Issue attempts to combine theoretical discussions, methodological considerations with experiences from the fields. It offers insights into possible links between non-probability sampling and hard-to-reach populations on the one hand, and, on the other hand, different approaches to address the aforementioned problems via the praxis of each methodology.
This special issue was inspired by a PUMA-Symposium 2017, which was organized by two of the guest editors of the Johannes Kepler University Linz (JKU), Johann Bacher and Andreas Quatember, within the PUMA-project of the Austrian social sciences. In this context, different sampling issues and different solution attempts were discussed. The editorship by two researchers of the Robert Koch Institute (RKI), Johannes Lemcke und Patrick Schmich, was guided by the Institute´s interest to a better integration of the hard-to-reach groups into its health monitoring system. The RKI, as the public health institute in Germany, has the obligation to monitor the health status of the whole population in order to offer policy makers valid information within the decision process. As a result of this commitment, various feasibility studies were carried out, which are presented in this special issue alongside initial results. In this respect the inclusion of elderly and people with migration background is a crucial task for the RKI.
The contributions can be divided into four groups
Of course, the assignment of a paper to a certain group is not distinct in every case. Nonetheless, the below grouping should provide some guidance.
- Two papers discuss the fundamental theoretical aspects of our topic.
- Two papers provide a comparison of probability and non-probability sampling from an applied perspective.
- Reports about experiences of concrete studies build the majority of the paper. Nine papers belong to this group. However, these are not only reports in a strict sense; they provide literature reviews, describe the designs and the underlying assumptions and reflect on the design. They cover migrants and refugees as hard-to-reach-groups mentioned by Willis et al. (2014) as well the elderly as one group sometimes ignored.
- The fourth group contains papers that can be labeled as “reflections and methodological proposals”. One paper suggests a model to increase the recruitment of old people; the second one applies simulations methods.
Probability and Nonprobability Sampling: Representative Surveys of hard-to-reach and hard-to-ask populations. Current surveys between the poles of theory and practiceSpecial issue
Inferences based on Probability Sampling or Nonprobability Sampling – Are They Nothing but a Question of Models?Special issue
The inferential quality of an available data set, be it from a probability sample or a nonprobability sample, is discussed under the standard of the representativeness of a sample with regard to interesting characteristics, which implicitly includes the consideration of the total survey error. The paper focuses on the assumptions that are made when calculating [...]
Representativeness, Sample surveys, Sampling techniques, Survey methodology, total survey error,
Possible Uses of Nonprobability Sampling for the Social SciencesSpecial issue
This paper compares the usability of data stemming from probability sampling with data stemming from nonprobability sampling. It develops six research scenarios that differ in their research goals and assumptions about the data generating process. It is shown that inferences from data stemming from nonprobability sampling implies demanding assumptions on the homogeneity of the units [...]
Causal Inference, Descriptive Inference, Fit-for-purpose, Interactions, Nonprobability sample, PATE, Probability sample,
Measuring sexual behaviours and attitudes in hard-to-reach groups. A comparison of a non-probability web survey with a national probability sample surveySpecial issue
Introduction: Hard-to-reach and minority groups are often at higher risk for adverse sexual health outcomes. While such groups are therefore of interest to sexual health researchers, it can be difficult to locate and recruit sufficient sample sizes using probability sampling methods. This study aims to establish whether web-panel surveys can provide a viable less resource [...]
hard to reach populations, non-probability samples, probability samples, sexual health, Web surveys,
Needles in Haystacks and Diamonds in the Rough: Using Probability and Nonprobability Methods to Survey Low-incidence PopulationsSpecial issue
While probability samples are generally the preferred approach in survey research, nonprobability samples continue to be of interest and are used for multiple purposes. We discuss the use of a convenience sample in one study and social media recruitment in another when probability-based samples fell short of reaching target sample sizes for low-incidence populations. Both [...]
convenience sampling, empirical comparisons, nonprobability samples, probability samples, rare populations, social media,
From peer to peer: Reaching migrants from sub-Saharan Africa with research on sexual health utilizing community-based participatory health researchSpecial issue
Migrants from sub-Saharan Africa (misSA) in Germany are disproportionally affected by HIV. To develop targeted interventions, it is necessary to collect data on knowledge, attitudes, behaviour and practices (KABP) regarding HIV and sexual health. However, misSA are difficult to reach and to sample: a) it is unknown how many people with an African migration background [...]
community-based participatory health research, HIV, KABP survey, migrants from sub-Saharan Africa, peer research, survey methods,
Integration of Migrant Populations into Health Monitoring in Germany: Results from a Feasibility StudySpecial issue
Background: Persons with migrant backgrounds (PMB) are considered ‘hard to reach’. To sustainably integrate migrant populations into health monitoring in Germany, the Robert Koch Institute (RKI) has launched the project Improving Health Monitoring in Migrant Populations (IMIRA), providing results on response rates, sample composition and the effectiveness of sequential interventions. Method: A multilingual feasibility study [...]
feasibility study, health monitoring, recruitment strategies, sequential mixed-mode-survey, surveying migrants,
Building a Sampling Frame for Migrant Populations via an Onomastic Approach – Lesson learned from the Austrian Immigrant Survey 2016Special issue
Immigrants are traditionally seen as hard to survey. Their number is often too small to be analysed via data gained in general population surveys, and registers to identify them are often missing or incomplete. Therefore, researchers are forced to use alternatives for sampling. In the case of the Austrian Immigrant Survey 2016, an onomastic (name-based) [...]
hard to reach populations, immigrants, Onomastic sampling, probability samples, sampling frame,
Sampling Refugees for an Educational Longitudinal SurveySpecial issue
In the years 2015 and 2016, in Germany more than half a million refugees were granted asylum or they were accepted being eligible for subsidiary protection. Thus, they got a residence permit. About 29% of the accepted refugees were younger than 18 years. To study education related integration issues in this group, in 2016 the [...]
educational research, Refugees, sampling,
How to Implement Respondent-Driven Sampling in Practice: Insights from Surveying 24-Hour Migrant Home Care WorkersSpecial issue
This article draws on the experience from an ongoing research project employing respondent-driven sampling (RDS) to survey (illicit) 24-hour home care workers. We highlight issues around the preparatory work and the fielding of the survey to provide researchers with useful insights on how to implement RDS when surveying populations for which the method has not [...]
hidden populations, illicit behaviours, practical implementation, respondent-driven sampling,
Sampling in Times of High Immigration: The Survey Process of the IAB-BAMF-SOEP Survey of RefugeesSpecial issue
Over the course of 2013 to 2016, over one million asylum seekers arrived in Germany, around 890,000 of them in 2015 alone. The growing refugee population posed a major challenge for Germany’s policy makers, civic administrators, and society at large, in finding new approaches to registration procedures, housing, and social and economic integration. To design [...]
complex samples, Nonresponse, rare populations, sampling design,
Including nursing home residents in a general population health survey in GermanySpecial issue
Nursing home residents (NHRs) are systematically excluded from the target populations of most population-based health surveys, which may result in biased prevalence estimates. Researchers who wish to include NHRs in surveys face several challenges including difficulty sampling and contacting NHRs and greater levels of functional impairments impeding participation. A population-wide, register-based, random sample of 8,000 [...]
coverage, hard-to-reach, nursing home residents, register-based sampling design, sequential mixed-mode design,
Effects of a sequential mixed-mode design on participation, contact and sample composition – Results of the pilot study “IMOA - Improving Health Monitoring in Old Age”Special issue
Existing health survey data of individuals who are 65+ years of age is limited due to the exclusion of the oldest old and physically or cognitively impaired individuals. This study aimed to assess the effects of a sequential mixed-mode design on (1) contact and response rates, (2) sample composition and (3) non-response bias. A register-based [...]
contact mode, data collection mode, non-response bias, older individuals, reasons for non-participation, sequential mixed-mode design,
Interviewing elderly in nursing homes – Respondent and survey characteristics as predictors of item nonresponseSpecial issue
Survey methodology is applied regularly in medical, nursing or social science studies examining elderly populations. Research in nursing home residents, where age-related or pathological declines in cognitive function are highly prevalent, faces several methodological challenges. The quality of survey data may be subject to population-specific measurement errors. In this article, data of two studies about [...]
Cognitive impairment, data quality, elderly populations, item nonresponse, nursing home residents,
How to reach ‘hard-to-reach’ older people for research: The TIBaR model of recruitmentSpecial issue
Recruiting older persons with diverse health statuses as participants in research projects is a challenge for health researchers, particularly because persons with health impairments and in socially disadvantaged living conditions are difficult to reach. This article presents a step model for gaining access to older people who are difficult to contact. The step model is [...]
hard to reach populations, older adults, Recruitment, research design,
Undercoverage of the elderly institutionalized population: The risk of biased estimates and the potentials of weightingSpecial issue
In most social surveys, the elderly institutionalized population is not part of the target population because it is considered as hard-to-reach and hard-to-interview. The deliberate exclusion of institutionalized elderly from survey samples might cause bias, like previous studies investigating institutionalized elderly persons and their transition to institutions implied. We use a Monte Carlo simulation based [...]
coverage bias, Institutionalized population, Monte Carlo Simulation, retirement and nursing homes, SHARE, Survey weighting,
