Properties of Bayes Factors Based on Test Statistics

Abstract.  This article examines the consistency, interpretation and application of Bayes factors constructed from standard test statistics. Primary conclusions are that Bayes factors based on multinomial and normal test statistics are consistent for suitable choices of the hyperparameters used to specify alternative hypotheses, and that such constructions can be extended to obtain consistent Bayes factors based on likelihood ratio statistics. A connection between Bayes factors based on likelihood ratio statistics and the Bayesian information criterion is exposed, as is a connection between Bayes factors based on F statistics and parametric Bayes factors based on normal-inverse gamma models. Similarly, Bayes factors based on chi-squared statistics for multinomial data are shown to provide accurate approximations to Bayes factors based on multinomial/Dirichlet models. An illustration of how the simple form of these Bayes factors can be exploited to generate easily interpretable summaries of the experimental 'weight of evidence' is provided.     

Sampling Returns for Realized Variance Calculations: Tick Time or Transaction Time?

This article introduces a new model for transaction prices in the presence of market microstructure noise in order to study the properties of the price process on two different time scales, namely, transaction time where prices are sampled with every transaction and tick time where prices are sampled with every price change. Both sampling schemes have been used in the literature on realized variance, but a formal investigation into their properties has been lacking. Our empirical and theoretical results indicate that the return dynamics in transaction time are very different from those in tick time and the choice of sampling scheme can therefore have an important impact on the properties of realized variance. For RV we find that tick time sampling is superior to transaction time sampling in terms of mean-squared-error, especially when the level of noise, number of ticks, or the arrival frequency of efficient price moves is low. Importantly, we show that while the microstructure noise may appear close to IID in transaction time, in tick time it is highly dependent. As a result, bias correction procedures that rely on the noise being independent, can fail in tick time and are better implemented in transaction time.     

Model-based measurement of latent risk in time series with applications

Summary.  Risk is at the centre of many policy decisions in companies, governments and other institutions. The risk of road fatalities concerns local governments in planning countermeasures, the risk and severity of counterparty default concerns bank risk managers daily and the risk of infection has actuarial and epidemiological consequences. However, risk cannot be observed directly and it usually varies over time. We introduce a general multivariate time series model for the analysis of risk based on latent processes for the exposure to an event, the risk of that event occurring and the severity of the event. Linear state space methods can be used for the statistical treatment of the model. The new framework is illustrated for time series of insurance claims, credit card purchases and road safety. It is shown that the general methodology can be effectively used in the assessment of risk.     

Bayesian locally optimal design of knockout tournaments

The elimination or knockout format is one of the most common designs for pairing competitors in tournaments and leagues. In each round of a knockout tournament, the losers are eliminated while the winners advance to the next round. Typically, the goal of such a design is to identify the overall best player. Using a common probability model for expressing relative player strengths, we develop an adaptive approach to pairing players each round in which the probability that the best player advances to the next round is maximized. We evaluate our method using simulated game outcomes under several data-generating mechanisms, and compare it to random pairings, to the standard knockout format, and to two variants of the standard format.     

Adolescent emotion regulation trajectories: The influence of parent and friend emotion socialization

With mounting evidence demonstrating the link between child emotion regulation (ER) and emotion socialization, we conducted a longitudinal study to understand (a) emotion-specific trajectories of adolescent ER and (b) how specific parent and friend emotion socialization strategies impact ER over 4 years. Participants were 209 adolescents (52.5% girls; M_age = 12.66 years; 75.7% White) and their parents. Latent growth curve models identified unique trajectories for anger and sadness/worry regulation. Anger regulation increased across time, whereas sadness/worry regulation remained highly stable longitudinally, lacking variance for growth modeling. Friend emotion socialization emerged as a more salient predictor of anger regulation than parent emotion socialization. Friend reward, override, and punish responses predicted initial levels. Friend punish and parent magnify responses predicted the slope.     

Students in out-of-home care: Their experiences of Transforming Educational Achievement for Children at Risk,an Australian education programme

Children living in out-of-home care are at greater risk of poor educational outcomes compared to other children. To address their educational needs, several programs have been developed. Within a qualitative paradigm, this study explored the experiences of students about their involvement in TEACHaR (Transforming Educational Achievement for Children at Risk), a specialized education programme. Eight students (aged 13 to 18 years) from the programme participated in individual, semi-structured interviews. Responses were analysed using Interpretive Phenomenological Analysis. Participants indicated that the programme provided individualized and flexible academic support, reduced their shame and embarrassment and provided them with more than academic support. They highlighted the importance of the student–educator relationship, and the need for encouragement and motivation to pursue their educational goals. Finally, findings report on how COVID-19 impacts on student experiences of the programme. Recommendations for the development and improvement of education programs for students in out-of-home care conclude this paper.     

“He invited me and didn't ask anything in return” Migration and Mobility as Vulnerabilities for Sexual Exploitation among Female Adolescents in Mexico

Although human trafficking is recognized as a major human rights violation, there is limited evidence regarding the vulnerabilities that contribute to female adolescents’ risk of being forced or coerced into the sex trade. Vulnerabilities such as gender‐based violence, economic and social inequalities have been shown to shape the risk of sexual exploitation among adolescents. In‐depth interviews (n=18) with current sex workers who reported being deceived or forced into the sex trade as adolescents (<17 years old) were analysed to explore their experiences of migration and mobility in Mexico. Driven by socio‐economic and vulnerabilities in home communities, adolescents often engaged in internal migration and mobility to other Mexican communities and states. Migration and mobility further predisposed them to social isolation, economic hardship and abuse, which were used as tools to trick them into the sex trade. Policies that support safer migration for adolescents in origin, transit, and destination communities are needed.