Tukey-Type Distributions in the Context of Financial Data

Abstract

In one-parameter (θ) families, we were not aware of explicit hypothesis testing scenarios where maximal invariant statistics failed to distinguish the models. We start with a concrete example (Sec. 2.2) to highlight such a hypothesis testing problem involving markedly different models. In this problem, because of the absence of a nontrivial uniformly most powerful invariant (UMPI) test, we briefly suggest two approaches to test the hypothesis. The first resolution (Sec. 3.1) is frequentist in nature. It utilizes a weight function on the parameter space and compares “average” distributions obtained under the null and alternative models in the sense of Wald (1947 Wald , A. ( 1947 ). Sequential Analysis . New York : Wiley . [Google Scholar] 1950 Wald , A. ( 1950 ). Statistical Decision Functions . New York : Wiley . [Google Scholar]). In contrast, a fully Bayesian resolution (Sec. 3.2) is also included. The note ends with a series of other interesting examples involving one-parameter families where maximal invariant statistics fail to distinguish the hypothesized models. The examples include easy-to-construct families of probability models involving only a single location or scale parameter θ.     

A statistical test for detecting discordance in rankings between k groups

In several research areas such as psychology, social science, and medicine, studies are conducted in which objects should be ranked by different judges/raters and the concordance of the different rankings is then analyzed. In such studies, it is also frequently of interest to compare the rankings between different groups of judges, e.g. female vs. male judges or judges from different professions. In the two-group case, the two-group concordance test of Schucany & Frawley can be employed for such a comparison. In this article, we propose an extension of this test enabling the comparison of rankings from more than two groups of judges. This test aims to detect disagreement in the average rankings of the objects between k groups with an at least moderate intra-group concordance. We evaluate this test in an extensive simulation study and in an application to data from an aesthetics study. This simulation study shows that the proposed test is able to detect differences between average rankings and performs well even in situations in which the disagreement is comparably small or the intra-group concordance is inhomogeneous.     

Effects of Social Anxiety on Emotional Mimicry and Contagion: Feeling Negative,but Smiling Politely

Socially anxiety may be related to a different pattern of facial mimicry and contagion of others’ emotions. We report two studies in which participants with different levels of social anxiety reacted to others’ emotional displays, either shown on a computer screen (Study 1) or in an actual social interaction (Study 2). Study 1 examined facial mimicry and emotional contagion in response to displays of happiness, anger, fear, and contempt. Participants mimicked negative and positive emotions to some extent, but we found no relation between mimicry and the social anxiety level of the participants. Furthermore, socially anxious individuals were more prone to experience negative emotions and felt more irritated in response to negative emotion displays. In Study 2, we found that social anxiety was related to enhanced mimicry of smiling, but this was only the case for polite smiles and not for enjoyment smiles. These results suggest that socially anxious individuals tend to catch negative emotions from others, but suppress their expression by mimicking positive displays. This may be explained by the tendency of socially anxious individuals to avoid conflict or rejection.     

A seasonal mixed-POT model to estimate high flood quantiles from different event types and seasons

Flood events can be caused by several different meteorological circumstances. For example, heavy rain events often lead to short flood events with high peaks, whereas snowmelt normally results in events of very long duration with a high volume. Both event types have to be considered in the design of flood protection systems. Unfortunately, all these different event types are often included in annual maximum series (AMS) leading to inhomogeneous samples. Moreover, certain event types are underrepresented in the AMS. This is especially unsatisfactory if the most extreme events result from such an event type. Therefore, monthly maximum data are used to enlarge the information spectrum on the different event types. Of course, not all events can be included in the flood statistics because not every monthly maximum can be declared as a flood. To take this into account, a mixture Peak-over-threshold model is applied, with thresholds specifying flood events of several types that occur in a season of the year. This model is then extended to cover the seasonal type of the data. The applicability is shown in a German case study, where the impact of the single event types in different parts of a year is evaluated.     

A Model Curriculum for Occupational Social Work

This paper reports the results of a survey experiment in which a national sample of NASW members was presented with systematically altered versions of a summary of a hypothetical study of casework effectiveness and asked to make judgments about the quality of the research, its importance to social work, and its significance for their own practice. It was found that although respondents distinguished between studies with good and bad research designs, their judgments of the quality of the research and its implications for their own practice were significantly influenced by whether the findings were positive or negative.     

Does Campus Diversity Promote Friendship Diversity? A Look at Interracial Friendships in College*

Objectives. One of the hopes of having diverse campus environments is that the daily interaction with students from different backgrounds will promote interracial understanding and friendship. However, it is not clear to what extent interactions and friendships are multiracial. This article examines the impact of college characteristics, social distance felt toward other groups, and precollege friendship diversity on the formation of interracial friendships in the first year of college. Methods. Using data from the National Longitudinal Survey of Freshmen, I examine how college characteristics, social distance felt toward other groups, and precollege friendship diversity affects the formation of interracial friendships in the first year of college. Results. The results show that while precollege experiences and initial attitudes do have an impact on the formation of interracial friendship in college, campus racial/ethnic diversity is also important in predicting friendship heterogeneity. Minorities have higher predicted friendship diversity than whites, but this difference nearly disappears in the most diverse schools due to the interactive effects of school diversity on friendship diversity for white students. Conclusions. This research provides evidence of the social benefits of assembling a diverse student body, particularly for white students, and can add to the debate over the continuation of affirmative action policies.     

Toward Improving Food Safety in the Domestic Environment: A Multi-Item Rasch Scale for the Measurement of the Safety Efficacy of Domestic Food-Handling Practices

To reduce consumer health risks from foodborne diseases that result from improper domestic food handling, consumers need to know how to safely handle food. To realize improvements in public health, it is necessary to develop interventions that match the needs of individual consumers. Successful intervention strategies are therefore contingent on identifying not only the practices that are important for consumer protection, but also barriers that prevent consumers from responding to these interventions. A measure of food safety behavior is needed to assess the effectiveness of different intervention strategies across different groups of consumers. A nationally representative survey was conducted in the Netherlands to determine which practices are likely conducted by which consumers. Participants reported their behaviors with respect to 55 different food-handling practices. The Rasch modeling technique was used to determine a general measure for the likelihood of an average consumer performing each food-handling behavior. Simultaneously, an average performance measure was estimated for each consumer. These two measures can be combined to predict the likelihood that an individual consumer engages in a specific food-handling behavior. A single "food safety" dimension was shown to underlie all items. Some potentially safe practices (e.g., use of meat thermometers) were reported as very difficult, while other safe practices were conducted by respondents more frequently (e.g., washing of fresh fruit and vegetables). A cluster analysis was applied to the resulting data set, and five segments of consumers were identified. Different behaviors may have different effects on microbial growth in food, and thus have different consequences for human health. Once the microbial relevance of the different consumer behaviors has been confirmed by experiments and modeling, the scale developed in the research reported here can be used to develop risk communication targeted to the needs of different consumer groups, as well as to measure the efficacy of different interventions.     

Social context and the experience of emotion

This study examines the relationship between the social context of events and emotional experience. For each of six emotions four different vignettes were devised. Two of these four events took place in private circumstances and two in public. Furthermore, the sociality of each situation was systematically varied, and subjects were presented with situations framed in one of three social contexts: alone, in the presence of a stranger, or in the presence of a friend. Subjects were asked for self-reports of emotional state, evaluations of pleasantness and loneliness, perceived ability to cope with negative situations, and the likelihood that they would share the emotional experience with another person. Anger was the only emotion that varied as a function of the social context manipulation, and this effect disappeared when evaluations of social context were controlled for. However, for all emotions, the intensity of experience differed between private and public situations, suggesting that sociality and emotionality are related at a more global level.