Usability testing with children: an application of Pedactice and Ticese methods

Graphic representation of clickable areas in computer interfaces should allow mental representations that facilitate systems navigation during the cognitive process. If it doesn't happen users can feel lost. When thinking about websites designed to children with both entertainment and educational intention these systems must stimulates this kind of users. As many other activities for children nowadays, many system are commonly used as support for contents explored in school, as a complement. The design of theses educational systems must have the compromise to allow these users navigate and feel capable to explore every part of these interfaces. This paper is focusing the results of Ticese and Pedactice methods and shows the importance of these results as an exploratory phase in a bigger research that evaluates interfaces with children. Quantitative and qualitative data were collected related to structuring the user's mental model, influenced by the graphic representation of hypertext areas in a children's educational site.     

Methodological Choices and Data Quality Issues for Official Poverty Measures: Evidences from Italy

Social Indicators Research - The application of new technologies and the implementation of e-government have profoundly modified management systems in public administrations. In this article we...     

Top incomes and the gender divide

In the recent research on top incomes, there has been little discussion of gender. A great deal is known about gender differentials in earnings, but how far does this carry over to total incomes? This paper investigates the gender divide at the top of the income distribution using tax record data for eight countries with individual taxation. It shows that women are strongly under-represented at the top of the distribution. Although the presence of women at the top has increased over time, the rise becomes smaller at the very top. The income gradient by gender has become more marked. The paper also shows that income composition differs by gender and exhibits significant changes over time, underlining the fact that it is not sufficient to look only at earned income.     

Detecting a change in wealth concentration without the knowledge of the wealth distribution

Consumption is commonly used as a proxy for permanent income. We go a step further by establishing the link between the distribution of consumption and that of permanent income in terms of dominance orderings. We introduce two new dominance orderings, the Generalized Top Lorenz test and the related affluence ordering. If consumption is a concave function of permanent income, we get an indirect and robust method to detect a change in permanent income concentration when the full stream of income receipts along the life cycle is unknown and only consumption data are available. Our application on US data for the period 1980?C2002 points out the difficult start in life of people belonging to the ??Baby loser generation?? (people born in the sixties) with respect to the previous and following cohort.     

Identification of Local Causal Effects with Missing Outcome Values and an Instrument for Non Response

Even in randomized experiments the identification of causal effects is often threatened by the presence of missing outcome values, with missingness possibly being non ignorable. We provide sufficient conditions under which the availability of a binary instrument for non response allows us to non parametrically point identify average causal effects in some latent subgroups of units, named Principal Strata, defined by their non response behavior in all possible combinations of treatment and instrument. Examples are provided as possible scenarios where our assumptions may be plausible.     

Estimation,prediction and interpretation of NGG random effects models: an application to Kevlar fibre failure times

We propose a class of Bayesian semiparametric mixed-effects models; its distinctive feature is the randomness of the grouping of observations, which can be inferred from the data. The model can be viewed under a more natural perspective, as a Bayesian semiparametric regression model on the log-scale; hence, in the original scale, the error is a mixture of Weibull densities mixed on both parameters by a normalized generalized gamma random measure, encompassing the Dirichlet process. As an estimate of the posterior distribution of the clustering of the random-effects parameters, we consider the partition minimizing the posterior expectation of a suitable class of loss functions. As a merely illustrative application of our model we consider a Kevlar fibre lifetime dataset (with censoring). We implement an MCMC scheme, obtaining posterior credibility intervals for the predictive distributions and for the quantiles of the failure times under different stress levels. Compared to a previous parametric Bayesian analysis, we obtain narrower credibility intervals and a better fit to the data. We found that there are three main clusters among the random-effects parameters, in accordance with previous frequentist analysis.     

Assessing repeatability and reproducibility using hierarchical modeling: a case-study of distortion product otoacoustic emissions

We present how the repeatability and reproducibility of a measurement device can be estimated from a suitably defined hierarchical linear model. The methodology is illustrated using a collection of eight data sets which consist of the distortion product otoacoustic emission recordings collected from both ears of ten young Sprague-Dawley rats at different frequencies under eight different recording conditions. We formulate a model which extends the commonly used one-way random effects model (5) to account for an experimental setup that is more elaborated than the ones traditionally used in interlaboratory experiments. The fitted model is easily interpretable and furnishes as a by-product the frequencies at which the highest response level is achieved under the eight recording conditions. These values together with the repeatability and reproducibility limits of the protocols are crucial in contributing to the enhancement of the research capabilities on the possible causes of hearing impairment.     

Optimal experiments in the presence of a learning effect: a problem suggested by software production

In software engineering empirical comparisons of different ways of writing computer code are often made. This leads to the need for planned experimentation and has recently established a new area of application of DoE. This paper is motivated by an experiment on the production of multimedia services on the web, performed at the Telecom Research Centre in Turin, where two different ways of developing code, with or without a framework, were compared. As the experiment progresses, the programmers performance improves as he/she undergoes a learning process; this must be taken into account as it may affect the outcome of the trial. In this paper we discuss statistical models and D-optimal plans for such experiments and indicate some heuristics which allow a much speedier search for the optimum. Solutions differ according to whether we assume that the learning process depends or not on the treatments.     

Demographic and territorial characteristics of COVID-19 cases and excess mortality in the European Union during the first wave

Journal of Population Research - This article explores for a large number of countries in the European Union (plus the United Kingdom) the main demographic differentials in positive tested COVID-19...     

Earnings uncertainty,precautionary saving,and moonlighting in Russia

Using a panel of 3,522 Russian households over the period 1994-2000, this paper tests the precautionary saving hypothesis, according to which households save to self-insure against uncertainty. We proxy uncertainty with a measure of earnings variability based on the subjective probability of primary job loss of household heads, and find that this variable generally has a strong positive effect on saving, supporting the precautionary saving hypothesis. This effect is however reversed for those households whose head holds more than one job, highlighting the role of moonlighting as a self-insurance mechanism that can be used in alternative to precautionary saving to smooth consumption in the presence of fluctuating earnings. Our findings are robust to different measures of uncertainty and estimation procedures.The authors are indebted to an anonymous referee and the editor T. Paul Schultz for helpful comments and suggestions. B-Y Kim gratefully acknowledges the financial support of the British Economic and Social Research Council (grant no. R000222463). A. Guariglia acknowledges the financial support of the University of Kent Faculty Research Fund Grant. Responsible editor: T. Paul Schultz