Assessing the use of mode preference as a covariate for the estimation of measurement effects between modes: a sequential mixed mode experiment

"Mixed mode surveys are presented as a solution to increasing survey costs and decreasing response rates. The disadvantage of such designs is the lack of control over mode effects and the interaction between selection and measurement effects. In a mixed mode survey, measurement effects can put into doubt data comparability between subgroups, or similarly between waves or rounds of a survey conducted using different modes. To understand the extent of measurement effects, selection and measurement effects between modes have to be disentangled. Almost all techniques to separate these effects depend on covariates that are assumed to be mode-insensitive and to fully explain selection effects. Most of the time, these covariates are sociodemographic variables that might be mode-insensitive, but fail to sufficiently explain selection effects. The aim of this research is to assess the performance of mode preference variables as covariates to evaluate selection and measurement effects between modes. In 2012, a mixed mode survey - a web questionnaire followed by face-to-face interviews - was conducted alongside the face-to-face European Social Survey in Estonia (Ainsaar et al., 2013). The questionnaire included mode preference items. In this paper, the effects of the trade-offs between the two assumptions on the precision of estimated selection and measurement effects are compared. The results show that while adding the mode preference to the propensity score model seems to increase the explanatory power of web participation, it decreases the correlation between propensity scores and target variables. In addition, the estimated selection and measurement effects do not always fit the expectation that more selection effects are explained and more measurement effects are detected." (author's abstract

Response Rates in the European Social Survey: Increasing, Decreasing, or a Matter of Fieldwork Efforts?

Response rates are declining increasing the risk of nonresponse error. The reasons for this decline are multiple: the rise of online surveys, mobile phones, and information requests, societal changes, greater awareness of privacy issues, etc. To combat this decline, fieldwork efforts have become increasingly intensive: widespread use of respondent incentives, advance letters, and an increased number of contact attempts. In addition, complex fieldwork strategies such as adaptive call scheduling or responsive designs have been implemented. The additional efforts to counterbalance nonresponse complicate the measurement of the increased difficulty of contacting potential respondents and convincing them to cooperate. To observe developments in response rates we use the first seven rounds of the European Social Survey, a biennial face-to-face survey. Despite some changes to the fieldwork efforts in some countries (choice of survey agency, available sample frame, incentives, number of contact attempts), many characteristics have been stable: effective sample size, (contact and) survey mode, and questionnaire design. To control for the different country composition in different rounds, we use a multilevel model with countries as level 2 units and response rates in each country-year combination as level 1 units. The results show a declining trend, although only round 7 has a significant negative effect

A data-driven approach to monitoring data collection in an online panel

Longitudinal or panel surveys suffer from panel attrition which may result in biased estimates. Online panels are no exceptions to this phenomenon, but offer great possibilities in monitoring and managing the data collection phase and response-enhancement features (e.g., reminders), due to real-time availability of paradata. This paper presents a data-driven approach to monitor the data collection phase and to inform the adjustment of response-enhancement features during data collection across online panel waves, which takes into account the characteristics of an ongoing panel wave. For this purpose, we study the evolution of the daily response proportion in each wave of a probability-based online panel. Using multilevel models, we predict the data collection evolution per wave day. In our example, the functional form of the data collection evolution is quintic. The characteristics affecting the shape of the data collection evolution are characteristics of the specific wave day and not of the panel wave itself. In addition, we simulate the monitoring of the daily response proportion of one panel wave and find that the timing of sending reminders could be adjusted after 20 consecutive panel waves to keep the data collection phase efficient. Our results demonstrate the importance of re-evaluating the characteristics of the data collection phase, such as the timing of reminders, across the lifetime of an online panel to keep the fieldwork efficient

Asymétrie d’information et marchés financiers : une synthèse de la littérature récente

Cet article est une synthèse des recherches récentes en matière d’asymétrie d’informations sur les marchés financiers. L’impact de différentes hypothèses sur l’existence et l’efficience informationnelle des équilibres est étudié. Le cas de la concurrence parfaite est d’abord analysé (Grossman et Stiglitz, 1980). Puis la concurrence imparfaite est analysée. On distingue deux cas, selon que le bruit qui empêche le prix d’être parfaitement révélateur provient d’une offre exogène (KyIe, 1985, 1989), ou d’une dotation aléatoire des agents informés (Glosten, 1989; Bhattacharya et Spiegel, 1990; Bossaerts et Hughson, 1991). Dans le premier cas, l’équilibre existe toujours. Dans le second cas, il n’existe que si le bruit est assez élevé ou si le support de sa distribution est borné.The impact of different hypotheses on the existence and informativeness of rational expectations equilibria is analyzed within a simple synthetic model. The case of perfect competition is first analyzed (Grossman and Stiglitz, 1980). Second imperfect competition with exogenous noise trading is studied (KyIe 1985, 1989). Informational efficiency is lower than in the previous case, because of the strategic behaviour of the insider. Third, imperfect competition without noise trader, but with unknown random endowments of the informed agent is analyzed (Glosten, 1989; Bhattacharya and Spiegel, 1990; Bossaerts and Hughson, 1991). In contrast with the previous case, equilibrium exists only if there is enough noise

Surveying Human Vulnerabilities across the Life Course

Este libro fue publicado en 2016 y esta es una edición corregida de 2018. El libro completo está sujeto a una licencia CC BY 4.0This open access book details tools and procedures for data collections of hard-to-reach, hard-to-survey populations. Inside, readers will discover first-hand insights from experts who share their successes as well as their failures in their attempts to identify and measure human vulnerabilities across the life course. Coverage first provides an introduction on studying vulnerabilities based on the Total Error Survey framework. Next, the authors present concrete examples on how to survey such populations as the elderly, migrants, widows and widowers, couples facing breast cancer, employees and job seekers, displaced workers, and teenagers during their transition to adulthood. In addition, one essay discusses the rationale for the use of life history calendars in studying social and psychological vulnerability while another records the difficulty the authors faced when trying to set-up an online social network to collect relevant data. Overall, this book demonstrates the importance to have, from the very beginning, a dialogue between specialists of survey methods and the researchers working on social dynamics across the life span. It will serve as an indispensable resource for social scientists interested in gathering and analyzing data on vulnerable individuals and populations in order to construct longitudinal data bases and properly target social policies.Peer reviewe

Estimating Components of Mean Squared Error to Evaluate the Benefits of Mixing Data Collection Modes

Mixed mode data collection designs are increasingly being adopted with the hope that they may reduce selection errors in single mode survey designs. Yet possible reductions in selection errors achieved by mixing modes may be offset by a potential increase in total survey error due to extra measurement error being introduced by the additional mode(s). Few studies have investigated this empirically, however. In the present study, we compute the Mean Squared Error (MSE) for a range of estimates using data from a mode comparison experiment. We compare two mixed mode designs (a sequential web plus mail survey, and a combined concurrent and sequential CATI plus mail survey) with a single mode mail survey. The availability of auxiliary data on the sampling frame allows us to estimate several components of MSE (sampling variance, non-coverage, nonresponse and measurement bias) for a number of sociodemographic and target variables. Overall, MSEs are lowest for the single mode survey, and highest for the CATI plus mail design, though this pattern is not consistent across all estimates. Mixing modes generally reduces total bias, but the relative contribution to total survey error from different sources varies by design and by variable type

Respondent-Driven Sampling

Summer school‘Reaching out to hard-to-survey groups among the poor’ HIVAstatus: publishe

Using time-related paradata to monitor the fieldwork

In this day and age, time is a critical element of anybody’s live, especially for the active population. The same holds for different facets of the survey process: time and timing are both linked to the survey costs and the data quality, two essential elements of a survey. During the data collection period, the available time of potential respondents play a key role in their decision to participate or not to the survey whilst the interviewer time, for telephone or face-to-face surveys, is an important factor in his/her capacity to recruit respondents. The timing of the visits, calls or sent-out of questionnaire/request and reminders has also been shown to be determining for survey participation. At the same time, requesting that interviewers work in the evening or at the weekend or making sure that the reminders to a Web or mail surveys are sent timely may have cost implications. Nonresponse error is not the only type of survey error to be linked to time: the time taken to answer a question, also called response latency, is known to echo the cognitive effort of the respondent and, hence, data quality. On the other hand, the interviewer speed can also influence data quality. Moreover the interviewer speed has been shown to be dependent of the rank of the interview. In this presentation, we will give a few examples on how time-related paradata can be used to detect survey error and used to improve data quality in a fieldwork monitoring perspective. Using the data from the European Social survey, we will illustrate how the yield of the fieldwork per time unit that can be derived from the contact forms and the interview speed that can be derived from timers could guide us in decision making with the aim to improve data quality during the fieldwork.status: publishe

Correlations in quantum systems with high level of symmetry

The understanding of entanglement in composite quantum systems can be rather involved if not impossible. One way to overcome the difficulties of studying many-body quantum systems and their correlations is to make use of any symmetry that they may exhibit. These symmetry properties can simplify the model we are studying, and allow us to make predictions about the behaviour of the system. By symmetry, we do not only mean group symmetry in this context, but rather special combinatorial properties. Examples of systems having a high level of symmetry are the permutation-invariant states corresponding to the mean field approximation but also the quasi-free states of fermion and boson systems which are linked to the Hartree-Fock approximation and used in solid states physics and Bose-Einstein condensation, and the VBS-states (valence bond solid states) represented by the DMRG (density matrix renormalisation group) approximation. In this work, we concentrate on the permutation-invariant states which we shall often call symmetric. In Chapter 1, states on finite and infinite spin systems are defined as well as the locality principle and entanglement. Some notion about quantum channels and their capacity are also introduced. The notions of symmetric and exchangeable states come from their classical equivalents: symmetric and exchangeable probabilities. In this regard, de Finetti's theorem is important as it characterises all exchangeable probabilities. In Chapter 2, we study these notions as well as their quantum equivalents. We then give a positivity criterion to recognise the two-site marginals of exchangeable states. This characterisation is useful as the decomposition given by Sto rmer's version of de Finetti's theorem is not unique, unless the decomposition is known for every N, where N denotes the system size, and hence recognising exchangeable states on two particles is far from being trivial. An application of this criterion is also given, namely we study the asymptotic ground state energy density of systems of composite particles. We prove that, under certain conditions, the asymptotic average ground state energy of such a system has a multiplicative behaviour, when the Hamiltonian is built out of ferromagnetic pair interactions. We conclude Chapter 2 with some remarks on the N-site marginals of exchangeable states, and how a positivity criterion similar to the one for two-site marginals could be found. We then turn our attention to symmetric states which are not necessarily exchangeable. An important result concerning symmetric probabilities on a system of N identical classical spin particles is that their distance to exchangeable probabilities is of order O(1/N). In Chapter 3, we obtain that the distance between the two-site marginals of the N-symmetric states and the exchangeable states is of order O(1/N) recovering partially the equivalent result for probabilities. We then consider the ground states of finite size mean field models, i.e., models for which the Hamiltonian is invariant under permutations of the particles. These ground states are examples of symmetric states, as they are obtained by taking the limit of the Gibbs states when the inverse temperature goes to infinity. When one takes the thermodynamical limit of such a model, one obtains an exchangeable state as asymptotic ground state. Hence, the distance between the ground state and the asymptotic ground state is of order O(1/N). In Chapter 3, for the qubit case, we give a correction of order O(1/N) of the two-site marginal of the ground state of a mean field model with respect to its asymptotic ground state, when the latter is pure. This allows one to study the fluctuations in such systems. Moreover the leading term of the concurrence between two qubits, or the entanglement of a qubit with the rest of the system, in such models can be calculated starting from the correction term. These quantities all vanish when the thermodynamical limit is taken as the asymptotic ground states are separable. We then apply this new result to the BCS-model, calculating the ground state energy of the finite size system. In Chapter 4, we consider quantum channels. We begin by recalling some conjectures about the additivity of their capacity and the amount of `mixedness' their noise creates. These conjectures are important when considering channels which are not memoryless, when the input states are entangled in time, or parallel channels, when the input spaces may be entangled in space. We then study in more detail the minimal second Renyi entropy output, linking it to the multiplicativity of the asymptotic ground state energy density of ferromagnetic mean field models under certain conditions. Therefore, we construct two ferromagnetic pair interactions starting from the Kraus decomposition of the quantum channel. Using this, we are able to prove the additivity of the minimal second Renyi entropy output for a class of channels. We conclude by giving some examples of such channels.status: publishe