Why do markets freeze?

Consider the sale of mortgages by a loan originator to a buyer. As widely noted, such a transaction is subject to a severe adverse selection problem: the originator has a natural information advantage and will attempt to sell only the worst mortgages. However, a second important feature of this transaction has received much less attention: both the seller and the buyer may have existing inventories of mortgages similar to those being sold. The authors analyze how the presence of such inventories affects trade. They use their model to discuss implications for regulatory intervention in illiquid markets.Mortgage loans

The Power of Demand: A General Equilibrium Analysis of Multi-Stage-Fabrication Economy with Inventories

Due to lack of models that can feature both output- and input-inventories simultaneously, several well known puzzles pertaining to inventory fluctuations and the business cycle have not been well explained by dynamic optimization theory. By presenting a general equilibrium, multi-stage production model of inventories with separate decisions to order, use, and stock input materials and to produce, sell, and store finished output, this paper offers not only a model of input-output inventories but also a neoclassical perspective on the theory of aggregate demand. It shows that due to production/ delivery lags, firms opt to hold both output- and input-inventories so as to guard against demand uncertainty at all stages of production. As a result, not only is production more volatile than sales but also is inputordering more volatile than input-usages, giving rise to a chain-multiplier mechanism that propagates and amplifies demand shocks at downstream towards upstream via input-output linkages. This multiplier effect induced by precautionary inventory investment at each production stage can explain several long-standing puzzles of the business cycle documented in the inventory literature.

Forecasting Sales of Slow and Fast Moving Inventories.

Adaptations of simple exponential smoothing are presented that aim to unify the task of forecasting demand for both slow and fast moving inventories. A feature of the adaptations is that they are designed to ensure that the resulting prediction distributions have only a nonnegative domain. A parametric bootstrap approach is proposed for generating empirical approximations for the so-called lead-time demand distribution, something required for inventory control calculations. The proposed methods are illustrated and their performance compared on real demand data for car parts.demand forecasting, inventory control, simulation, parametric bootstrapping, time series analysis.

A cross-linguistic database of phonetic transcription systems

Contrary to what non-practitioners might expect, the systems of phonetic notation used by linguists are highly idiosyncratic. Not only do various linguistic subfields disagree on the specific symbols they use to denote the speech sounds of languages, but also in large databases of sound inventories considerable variation can be found. Inspired by recent efforts to link cross-linguistic data with help of reference catalogues (Glottolog, Concepticon) across different resources, we present initial efforts to link different phonetic notation systems to a catalogue of speech sounds. This is achieved with the help of a database accompanied by a software framework that uses a limited but easily extendable set of non-binary feature values to allow for quick and convenient registration of different transcription systems, while at the same time linking to additional datasets with restricted inventories. Linking different transcription systems enables us to conveniently translate between different phonetic transcription systems, while linking sounds to databases allows users quick access to various kinds of metadata, including feature values, statistics on phoneme inventories, and information on prosody and sound classes. In order to prove the feasibility of this enterprise, we supplement an initial version of our cross-linguistic database of phonetic transcription systems (CLTS), which currently registers five transcription systems and links to fifteen datasets, as well as a web application, which permits users to conveniently test the power of the automatic translation across transcription systems

Inventories, Markups and Real Rigidities in Sticky Price Models of the Canadian Economy

Recent New Keynesian models of macroeconomy view nominal cost rigidities, rather than nominal price rigidities, as the key feature that accounts for the observed persistence in output and inflation. Kryvtsov and Midrigan (2010a,b) reassess these conclusions by combining a theory based on nominal rigidities and storable goods with direct evidence on inventories for the U.S. This paper applies Kryvtsov and Midrigan’s model to the case of Canada. The model predicts that if costs of production are sticky and markups do not vary much in response to, say, expansionary monetary policy, firms react by excessively accumulating inventories in anticipation of future cost increases. In contrast, in the Canadian data inventories are fairly constant over the cycle and in response to changes in monetary policy. Similarly to Kryvtsov and Midrigan, we show that markups must decline sufficiently in times of a monetary expansion in order to reduce firms’ incentive to hold inventories and thus bring the model’s inventory predictions in line with the data. The model consistent with salient features of the dynamics of inventories in the Canadian data implies that countercyclical markups account for a sizable (50-80%) fraction of the response of real variables to monetary shocks.Business fluctuations and cycles; Transmission of monetary policy

Contextual factors among indiscriminate or larger attacks on food or water supplies, 1946-2015

This research updates previous inventories of malicious attacks on food and water to include data from 1946 through mid-2015. A systematic search of news reports, databases and previous inventories of poisoning events was undertaken. Incidents that threatened or were intended to achieve direct harm to humans, and that were either relatively large (number of victims > 4 or indiscriminate in intent or realisation were included. Agents could be chemical, biological or radio-nuclear. Reports of candidate incidents were subjected to systematic inclusion and exclusion criteria as well as validity analysis (not always clearly undertaken in previous inventories of such attacks). We summarise contextual aspects of the attacks that may be important for scenario prioritisation, modelling and defensive preparedness. Opportunity is key to most realised attacks, particularly access to dangerous agents. The most common motives and relative success rate in causing harm were very different between food and water attacks. The likelihood that people were made ill or died also varied by food/water mode, and according to motive and opportunity for delivery of the hazardous agent. Deaths and illness associated with attacks during food manufacture and prior to sale have been fewer than those in some other contexts. Valuable opportunities for food defence improvements are identified in other contexts, especially food prepared in private or community settings

(Un)markedness of trills : the case of Slavic r-palatalisation

This paper evaluates trills [r] and their palatalized counterparts [rj] from the point of view of markedness. It is argued that [r]s are unmarked sounds in comparison to [rj]s which follows from the examination of the following parameters: (a) frequency of occurrence, (b) articulatory and aerodynamic characteristics, (c) perceptual features, (d) emergence in the process of language acquisition, (e) stability from a diachronic point of view, (f) phonotactic distribution, and (g) implications. Several markedness aspects of [r]s and [rj] are analyzed on the basis of Slavic languages which offer excellent material for the evaluation of trills. Their phonetic characteristics incorporated into phonetically grounded constraints are employed for a phonological OT-analysis of r-palatalization in two selected languages: Polish and Czech

Unsupervised, Knowledge-Free, and Interpretable Word Sense Disambiguation

Interpretability of a predictive model is a powerful feature that gains the trust of users in the correctness of the predictions. In word sense disambiguation (WSD), knowledge-based systems tend to be much more interpretable than knowledge-free counterparts as they rely on the wealth of manually-encoded elements representing word senses, such as hypernyms, usage examples, and images. We present a WSD system that bridges the gap between these two so far disconnected groups of methods. Namely, our system, providing access to several state-of-the-art WSD models, aims to be interpretable as a knowledge-based system while it remains completely unsupervised and knowledge-free. The presented tool features a Web interface for all-word disambiguation of texts that makes the sense predictions human readable by providing interpretable word sense inventories, sense representations, and disambiguation results. We provide a public API, enabling seamless integration.Comment: In Proceedings of the the Conference on Empirical Methods on Natural Language Processing (EMNLP 2017). 2017. Copenhagen, Denmark. Association for Computational Linguistic