Bivariate pointing movements on large touch screens: investigating the validity of a refined Fitts' Law

On the basis of three empirical studies Fitts' Law was refined for bivariate pointing tasks on large touch screens. In the first study different target width parameters were investigated. The second study considered the effect of the motion angle. Based on the results of the two studies a refined model for movement time in human-computer interaction was formulated. A third study, which is described here in detail, concerns the validation of the refined model. For the validation study 20 subjects had to execute a bivariate pointing task on a large touch screen. In the experimental task 250 rectangular target objects were displayed at a randomly chosen position on the screen covering a broad range of ID values (ID= [1.01; 4.88]). Compared to existing refinements of Fitts' Law, the new model shows highest predictive validity. A promising field of application of the model is the ergonomic design and evaluation of project management software. By using the refined model, software designers can calculate a priori the appropriate angular position and the size of buttons, menus or icons.     

The Effect of Visas on Migration Processes

The effectiveness of migration policies has been widely contested. However, because of methodological and conceptual limitations, evidence has remained inconclusive. Moreover, prior studies focus on the effects of policies on inflows and fail to assess the simultaneous effect of policies on outflows. This is essential from a theoretical point of view as immigration restrictions may reduce both inflows and outflows and, hence, overall circulation. This renders the effect of immigration restrictions on net migration theoretically ambiguous. To fill this gap, and using unique migration and visa data from the Determinants of International Migration (DEMIG) project, this paper assesses the short‐ and long‐term effects of travel visa policy regimes on bilateral immigration and emigration dynamics. The results suggest that travel visa policies significantly decrease inflows, but this effect is undermined by decreasing outflows of the same migrant groups. This confirms that migration restrictions decrease circulation and tend to encourage long‐term settlement, and thereby sharply reduce the responsiveness of migration to economic fluctuations in destination and origin societies. We also identify asymmetric policy effects with migration flows declining only very gradually after a visa introduction but increasing almost immediately after visa removal.     

The Gravity of High-Skilled Migration Policies

Combining unique, annual, bilateral data on labor flows of highly skilled immigrants for 10 OECD destinations between 2000 and 2012, with new databases comprising both unilateral and bilateral policy instruments, we present the first judicious cross-country assessment of policies aimed to attract and select high-skilled workers. Points-based systems are much more effective in attracting and selecting high-skilled migrants than requiring a job offer, labor market tests, and shortage lists. Offers of permanent residency, while attracting the highly skilled, overall reduce the human capital content of labor flows because they prove more attractive to non-high-skilled workers. Bilateral recognition of diploma and social security agreements foster greater flows of high-skilled workers and improve the skill selectivity of immigrant flows. Conversely, double taxation agreements deter high-skilled migrants, although they do not alter overall skill selectivity. Our results are robust to a variety of empirical specifications that account for destination-specific amenities, multilateral resistance to migration, and the endogeneity of immigration policies.     

That Man Behind the Curtain: Investigating the Sexual Online Dating Behavior of Men Who Have Sex With Men but Hide Their Same-Sex Sexual Attraction in Offline Surroundings

This study investigates how men who have sex with men (MSM) use chat and dating sites based on theories of stigma-related offline behavior and online self-disclosure. We hypothesize that hidden MSM (those who self-label as heterosexual or who hide their same-sex sexual attraction from family, friends, acquaintances, or a female romantic partner) differ from open MSM in how they behave on gay chat and dating sites and in offline gay venues. Drawing on a survey of 12,002 MSM, we show that hidden MSM tend to mask their identity on gay chat and dating sites while avoiding offline gay venues. They also focus more strongly on online sexual activities (e.g., masturbating during online chats) when using gay chat and dating sites. However, they spend the same amount of time on these sites, and they use them to initiate offline sexual encounters as often and as fast as open MSM.     

Determinants of savings and remittances: empirical evidence from immigrants to Germany

This paper investigates the determinants of migrants’ financial transfers to their home country using German data. A double-hurdle model is applied to analyze the determinants of the propensity to send transfers to the country of origin and the amount of transfers. The findings reveal that return intentions positively affect financial transfers of immigrants to their home country. The results of a decomposition analysis suggest that only a small part of the gap in financial transfers between temporary and permanent migrants can be attributed to differences in observable characteristics.     

The savings behavior of temporary and permanent migrants in Germany

This paper examines the relative savings position of migrant households in West Germany paying particular attention to differences between temporary and permanent migrants. Our findings reveal significant differences in the savings rates between German natives and immigrants. If remittances are treated as savings, however, migrants who intend to return to their home country save significantly more than comparable natives. The results of a decomposition analysis indicate that slightly more than half of the differences in the savings rate between Germans and permanent migrants and almost 70% between temporary and permanent migrants can be attributed to differences in observable characteristics.     

Generic Identifiability of Linear Structural Equation Models by Ancestor Decomposition

Linear structural equation models, which relate random variables via linear interdependencies and Gaussian noise, are a popular tool for modelling multivariate joint distributions. The models correspond to mixed graphs that include both directed and bidirected edges representing the linear relationships and correlations between noise terms, respectively. A question of interest for these models is that of parameter identifiability, whether or not it is possible to recover edge coefficients from the joint covariance matrix of the random variables. For the problem of determining generic parameter identifiability, we present an algorithm building upon the half‐trek criterion. Underlying our new algorithm is the idea that ancestral subsets of vertices in the graph can be used to extend the applicability of a decomposition technique.     

Ein metrikbasierter Ansatz zur Messung der Aktualit?t von Daten in Informationssystemen

Due to the importance of using up-to-date data in information systems, this paper analyzes how the data quality dimension currency can be measured. Therefore, we design a probability based metric that allows for an objective and to a great extent automated assessment of data’s currency. In contrast to existing approaches, the resulting values of the new metric meet important requirements such as ratio scale and can be interpreted as probabilities. Hence, they can also be applied to calculate expected values for decision making in a methodically well-founded manner. Moreover, the metric can be adapted to the context of a particular application considering both, the specific characteristics of attribute values and supplemental data stored in the information system. The evaluation of the approach is based on six requirements for data quality metrics. Furthermore, the case of a mobile services provider illustrates the metric’s applicability and its practical benefit.     

A SINful approach to Gaussian graphical model selection

Multivariate Gaussian graphical models are defined in terms of Markov properties, i.e., conditional independences, corresponding to missing edges in the graph. Thus model selection can be accomplished by testing these independences, which are equivalent to zero values of corresponding partial correlation coefficients. For concentration graphs, acyclic directed graphs, and chain graphs (both LWF and AMP classes), we apply Fisher's z-transform, Šidák's correlation inequality, and Holm's step-down procedure to simultaneously test the multiple hypotheses specified by these zero values. This simple method for model selection controls the overall error rate for incorrect edge inclusion. Prior information about the presence and/or absence of particular edges can be readily incorporated.