A Bayesian information criterion for singular models

We consider approximate Bayesian model choice for model selection problems that involve models whose Fisher-information matrices may fail to be invertible along other competing submodels. Such singular models do not obey the regularity conditions underlying the derivation of Schwarz's Bayesian information criterion (BIC) and the penalty structure in BIC generally does not reflect the frequentist large-sample behavior of their marginal likelihood. While large-sample theory for the marginal likelihood of singular models has been developed recently, the resulting approximations depend on the true parameter value and lead to a paradox of circular reasoning. Guided by examples such as determining the number of components of mixture models, the number of factors in latent factor models or the rank in reduced-rank regression, we propose a resolution to this paradox and give a practical extension of BIC for singular model selection problems

Validating simulated interaction for retrieval evaluation

A searcher’s interaction with a retrieval system consists of actions such as query formulation, search result list interaction and document interaction. The simulation of searcher interaction has recently gained momentum in the analysis and evaluation of interactive information retrieval (IIR). However, a key issue that has not yet been adequately addressed is the validity of such IIR simulations and whether they reliably predict the performance obtained by a searcher across the session. The aim of this paper is to determine the validity of the common interaction model (CIM) typically used for simulating multi-query sessions. We focus on search result interactions, i.e., inspecting snippets, examining documents and deciding when to stop examining the results of a single query, or when to stop the whole session. To this end, we run a series of simulations grounded by real world behavioral data to show how accurate and responsive the model is to various experimental conditions under which the data were produced. We then validate on a second real world data set derived under similar experimental conditions. We seek to predict cumulated gain across the session. We find that the interaction model with a query-level stopping strategy based on consecutive non-relevant snippets leads to the highest prediction accuracy, and lowest deviation from ground truth, around 9 to 15% depending on the experimental conditions. To our knowledge, the present study is the first validation effort of the CIM that shows that the model’s acceptance and use is justified within IIR evaluations. We also identify and discuss ways to further improve the CIM and its behavioral parameters for more accurate simulations

Explanation and Elaboration Document for the STROBE-Vet Statement: Strengthening the Reporting of Observational Studies in Epidemiology—Veterinary Extension

The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement was first published in 2007 and again in 2014. The purpose of the original STROBE was to provide guidance for authors, reviewers and editors to improve the comprehensiveness of reporting; however, STROBE has a unique focus on observational studies. Although much of the guidance provided by the original STROBE document is directly applicable, it was deemed useful to map those statements to veterinary concepts, provide veterinary examples and highlight unique aspects of reporting in veterinary observational studies. Here, we present the examples and explanations for the checklist items included in the STROBE-Vet Statement. Thus, this is a companion document to the STROBE-Vet Statement Methods and process document, which describes the checklist and how it was developed

Pilot interministerial operation for remote sensing

Advantages and disadvantages of traditional methods of obtaining required information for land and resources management and the possibilities of remote sensing are discussed. The services available, organization and objectives of the pilot operation are presented. Emphasis is placed on multidisciplinary dialog among designers, builders, operators, interpreters and users in all phases. The principles, operation and practical applications of remote sensing systems and processing systems under the pilot operation are presented

Multiple Testing Procedures for the Analysis of Microarray Data

We reviewed literature about various multiple testing techniques, especially addressing microarray analyses and small sample sizes, and reanalyzed data from Yuen et al. (Physiological Genomics, 2006) which compared the effect of HgCl2 and Ischemia/Reperfusion injuries on rat kidney tissues. Our analysis uses only 22 rats with small numbers of rats in each treatment group, and 9,501 genes under study. We used empirical Bayes (EB) and permutation testing (implemented in Bioconductor) in an effort to identify differentially expressed genes. EB identified a large number of genes as differentially expressed, including both previously identified and newly identified genes. The newly identified genes appear to have biological functions similar to those previously identified. We also recognized power differences between EB and permutation tests, possibly due to nonnormality of the data but also because permutation tests do not make use of all available information in the data

Naked Exclusion: Towards a Behavioral Approach to Exclusive Dealing

We report experimental results on exclusive dealing inspired by the literature on "naked exclusion". Our key findings are: First, exclusion of a more efficient entrant is a widespread phenomenon in lab markets. Second, allowing incumbents to discriminate between buyers increases exclusion rates compared to the non-discriminatory case only when payments to buyers can be offered sequentially and secretly. Third, allowing discrimination does not lead to significant decreases in costs of exclusion. Accounting for the observation that buyers are more likely to accept an exclusive deal the higher is the payment, substantially improves the fit between theoretical predictions and observed behavior.exclusive dealing;entry deterrence;foreclosure;contracts;externalities;coordination;experiments

The Optimality of Simple Contracts: Moral Hazard and Loss Aversion

This paper extends the standard principal-agent model with moral hazard to allow for agents having reference- dependent preferences according to Köszegi and Rabin (2006, 2007). The main finding is that loss aversion leads to fairly simple contracts. In particular, when shifting the focus from standard risk aversion to loss aversion, the optimal contract is a simple bonus contract, i.e. when the agent's performance exceeds a certain threshold he receives a fixed bonus payment. Moreover, if the agent is sufficiently loss averse, it is shown that the first-order approach is not necessarily valid. If this is the case the principal may be unable to fine-tune incentives. Strategic ignorance of information by the principal, however, allows to overcome these problems and may even reduce the cost of implementation.Agency Model; Moral Hazard; Reference-Dependent Preferences; Loss Aversion