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Université de Fribourg

Transnational machine learning with screens for flagging bid-rigging cartels

Huber, Martin ; Imhof, David ; Ishii, Rieko

(Working Papers SES ; 519)

We investigate the transnational transferability of statistical screening methods originally developed using Swiss data for detecting bid-rigging cartels in Japan. We find that combining screens for the distribution of bids in tenders with machine learning to classify collusive vs. competitive tenders entails a correct classification rate of 88% to 93% when training and testing the method...

Université de Fribourg

Striatal reactivity to reward under threat-of-shock and working memory load in adults at increased familial risk for major depression: A preliminary study

Gaillard, Claudie ; Guillod, Matthias ; Ernst, Monique ; Federspiel, Andrea ; Schoebi, Dominik ; Recabarren, Romina Evelyn ; Ouyang, Xinyi ; Mueller-Pfeiffer, Christoph ; Horschg, Antje ; Homan, Philipp ; Wiest, Roland ; Hasler, Gregor ; Martin-Soelch, Chantal

In: NeuroImage: Clinical, 2020, vol. 26, p. 102193

Introduction: Anhedonia, a core symptom of Major Depressive Disorder (MDD), manifests as a lack or loss of motivation as reflected by decreased reward responsiveness, at both behavioral and neural (i.e., striatum) levels. Exposure to stressful life events is another important risk factor for MDD. However, the mechanisms linking reward-deficit and stress to MDD remain poorly understood. Here,...

Université de Fribourg

Machine learning approach for flagging incomplete bid-rigging cartels

Wallimann, Hannes ; Imhof, David ; Huber, Martin

(Working Papers SES ; 513)

We propose a new method for flagging bid rigging, which is particularly useful for detecting incomplete bid-rigging cartels. Our approach combines screens, i.e. statistics derived from the distribution of bids in a tender, with machine learning to predict the probability of collusion. As a methodological innovation, we calculate such screens for all possible subgroups of three or four bids...

Université de Fribourg

Notes on the cheek region of the Late Jurassic theropod dinosaur Allosaurus

Evers, Serjoscha W. ; Foth, Christian ; Rauhut, Oliver W.M.

In: PeerJ, 2020, vol. 8, p. e8493

Allosaurus, from the Late Jurassic of North America and Europe, is a model taxon for Jurassic basal tetanuran theropod dinosaurs. It has achieved an almost iconic status due to its early discovery in the late, 19th century, and due to the abundance of material from the Morrison Formation of the western U.S.A., making Allosaurus one of the best-known theropod taxa. Despite this, various...

Université de Fribourg

Late Jurassic theropod dinosaur bones from the Langenberg Quarry (Lower Saxony, Germany) provide evidence for several theropod lineages in the central European archipelago

Evers, Serjoscha W. ; Wings, Oliver

In: PeerJ, 2020, vol. 8, p. e8437

Marine limestones and marls in the Langenberg Quarry provide unique insights into a Late Jurassic island ecosystem in central Europe. The beds yield a varied assemblage of terrestrial vertebrates including extremely rare bones of theropod from theropod dinosaurs, which we describe here for the first time. All of the theropod bones belong to relatively small individuals but represent a wide...

Université de Fribourg

An introduction to flexible methods for policy evaluation

Huber, Martin

(Working Papers SES ; 504)

This chapter covers different approaches to policy evaluation for assessing the causal effect of a treatment or intervention on an outcome of interest. As an introduction to causal inference, the discussion starts with the experimental evaluation of a randomized treatment. It then reviews evaluation methods based on selection on observables (assuming a quasi-random treatment given observed...

Université de Fribourg

A non-archaeopterygid avialan theropod from the Late Jurassic of southern Germany

Rauhut, Oliver W. M. ; Tischlinger, Helmut ; Foth, Christian

In: eLife, 2019, vol. 8, p. e43789

The Late Jurassic ‘Solnhofen Limestones’ are famous for their exceptionally preserved fossils, including the urvogel Archaeopteryx, which has played a pivotal role in the discussion of bird origins. Here we describe a new, non-archaeopterygid avialan from the Lower Tithonian Mörnsheim Formation of the Solnhofen Archipelago, Alcmonavis poeschli gen. et sp. nov. Represented by a right...