Systematic handling of missing data in complex study designs – experiences from the Health 2000 and 2011 Surveys

We present a systematic approach to the practical and comprehensive handling of missing data motivated by our experiences of analyzing longitudinal survey data. We consider the Health 2000 and 2011 Surveys (BRIF8901) where increased non-response and non-participation from 2000 to 2011 was a major issue. The model assumptions involved in the complex sampling design, repeated measurements design, non-participation mechanisms and associations are presented graphically using methodology previously defined as a causal model with design, i.e. a functional causal model extended with the study design. This tool forces the statistician to make the study design and the missing-data mechanism explicit. Using the systematic approach, the sampling probabilities and the participation probabilities can be considered separately. This is beneficial when the performance of missing-data methods are to be compared. Using data from Health 2000 and 2011 Surveys and from national registries, it was found that multiple imputation removed almost all differences between full sample and estimated prevalences. The inverse probability weighting removed more than half and the doubly robust method 60% of the differences. These findings are encouraging since decreasing participation rates are a major problem in population surveys worldwide.     

On future household structure

Summary.  We develop a method for computing probabilistic household forecasts which quantifies uncertainty in the future number of households of various types in a country. A probabilistic household forecast helps policy makers, planners and other forecast users in the fields of housing, energy, social security etc. in taking appropriate decisions, because some household variables are more uncertain than others. Deterministic forecasts traditionally do not quantify uncertainty. We apply the method to data from Norway. We find that predictions of future numbers of married couples, cohabiting couples and one-person households are more certain than those of lone parents and other private households. Our method builds on an existing method for computing probabilistic population forecasts, combining such a forecast with a random breakdown of the population according to household position (single, cohabiting, living with a spouse, living alone etc.). In this application, uncertainty in the total numbers of households of different types derives primarily from random shares, rather than uncertain future population size. A similar method could be applied to obtain probabilistic forecasts for other divisions of the population, such as household size, health or disability status, region of residence and labour market status.     

Improving the Well-Being and Safety of Children with Sensors and Mobile Technology

The well-being and safety of children and young people are important aspects in all contexts of everyday life. In particular, a feeling of insecurity might be a problem when being alone. Bullying is also common among school-age children and teenagers. Hence, there is a great need for personalized support systems to resolve these problems. This article describes a new area of research in sensor and social web development to help indicate children’s insecurity in their daily environment. Deeper integration of sensors and the social web would allow us to foresee drastic changes in communities and new social–ethical scenarios will emerge.     

Accountability as a Warrant for Trust: An Experiment on Sanctions and Justifications in a Trust Game

Accountability is present in many types of social relations; for example, the accountability of elected representatives to voters is the key characteristic of representative democracy. We distinguish between two institutional mechanisms of accountability, i.e., opportunity to punish and requirement of a justification, and examine the separate and combined effects of these mechanisms on individual behavior. For this purpose, we designed a decision-making experiment where subjects engage in a three-player trust game with two senders and one responder. We ask whether holding the responder accountable increases senders’ and responders’ contributions in a trust game. When restricting the analysis to the first round, the requirement of justification seems to have a positive impact on senders’ contributions. When the game is played repeatedly, the experience of previous rounds dominates the results and significant treatment effects are no longer seen. We also find that responders tend to justify their choices in terms of reciprocity, which is in line with observed behavior. Moreover, the treatment combining punishment and justification hinders justifications that appeal to pure self-interest.

     

Efficient initial designs for binary response data

In this paper we introduce a binary search algorithm that efficiently finds initial maximum likelihood estimates for sequential experiments where a binary response is modeled by a continuous factor. The problem is motivated by switching measurements on superconducting Josephson junctions. In this quantum mechanical experiment, the current is the factor controlled by the experimenter and a binary response indicating the presence or the absence of a voltage response is measured. The prior knowledge on the model parameters is typically poor, which may cause the common approaches of initial estimation to fail. The binary search algorithm is designed to work reliably even when the prior information is very poor. The properties of the algorithm are studied in simulations and an advantage over the initial estimation with equally spaced factor levels is demonstrated. We also study the cost-efficiency of the binary search algorithm and find the approximately optimal number of measurements per stage when there is a cost related to the number of stages in the experiment.     

Taming predators through photography

In this article we examine an innovative application of visual communication and social science methods, moving the study of indigenous media from the purely academic realm into pediatric health research. Through Video Intervention/Prevention Assessment (VIA), children and adolescents who share a medical condition create visual narratives of their lives with chronic disease to show and tell their illness experiences to health care providers. Clinicians routinely plan medical management with limited knowledge of how patients interact with disease in their “real life” physical, psychological, and social environments. VIA asks young patients to teach clinicians the realities of day‐to‐day life with illness, yielding unique insights that can guide the development of more realistic, more humane, and ultimately more effective medical care. We describe the VIA methodology, a pilot study of asthma, and the illness experiences shown and told by VIA Asthma participants. Not only did VIA generate useful research findings, it also produced visual documents of the child's illness experience that can serve as tools for influencing policy, advocating for patients, and educating health care providers, patients, and their families.     

Experimental designs for binary data in switching measurements on superconducting Josephson junctions

Summary.  We study the optimal design of switching measurements of small Josephsonjunction circuits which operate in the macroscopic quantum tunnelling regime. In the experiment, sequences of current pulses are applied to the Josephson junction sample, while the voltage over the structure is monitored. The appearance of a voltage pulse to a single applied current pulse, being governed by the laws of quantum mechanics, is purely random. Starting from the D -optimality criterion we derive the optimal design for the estimation of the unknown parameters of the underlying Gumbel-type distribution. As a practical method for the measurements, we propose a sequential design that combines heuristic search for initial estimates and maximum likelihood estimation. The design presented has immediate applications in the area of superconducting electronics, implying faster data acquisition. The experimental results presented confirm the usefulness of the method.     

Non-parametric Bayesian Estimation of a Spatial Poisson Intensity

A method introduced by Arjas & Gasbarra (1994) and later modified by Arjas & Heikkinen (1997) for the non-parametric Bayesian estimation of an intensity on the real line is generalized to cover spatial processes. The method is based on a model approximation where the approximating intensities have the structure of a piecewise constant function. Random step functions on the plane are generated using Voronoi tessellations of random point patterns. Smoothing between nearby intensity values is applied by means of a Markov random field prior in the spirit of Bayesian image analysis. The performance of the method is illustrated in examples with both real and simulated data.     

Achievement Orientations,School Adjustment,and Well-being: A Longitudinal Study

This study set out to identify the kinds of achievement orientations that adolescents show, and to examine the kinds of antecedents and consequences the use of a particular orientation has. The participants were 734 Swedish adolescents (335 boys and 399 girls) who filled in questionnaires measuring their achievement beliefs and behaviors, depressive symptoms, engagement with school, and norm-breaking behavior. By using clustering-by-cases analysis, five achievement orientation groups were identified: optimism, defensive-pessimism, self-handicapping, and learned helplessness, and a group showing average levels of criteria variables. The results showed further that a decrease in depressive symptoms and an increase in engagement with school predicted a move to the use of optimistic and defensive-pessimistic groups, whereas a reverse pattern predicted a move to the helplessness and self-handicapping groups. Moreover, the optimistic and defensive-pessimistic achievement orientations at Time 1 predicted an increase in engagement with school and a decrease in depressive symptoms later on, whereas self-handicapping and learned helplessness predicted a decrease in engagement with school and increases in depressive symptoms and norm-breaking behavior.