On the Accuracy of Group Credences

to appear in Szabó Gendler, T. & J. Hawthorne (eds.) Oxford Studies in Epistemology volume 6 We often ask for the opinion of a group of individuals. How strongly does the scientific community believe that the rate at which sea levels are rising increased over the last 200 years? How likely does the UK Treasury think it is that there will be a recession if the country leaves the European Union? What are these group credences that such questions request? And how do they relate to the individual credences assigned by the members of the particular group in question? According to the credal judgment aggregation principle, Linear Pooling, the credence function of a group should be a weighted average or linear pool of the credence functions of the individuals in the group. In this paper, I give an argument for Linear Pooling based on considerations of accuracy. And I respond to two standard objections to the aggregation principle

2004 Cereals reveal an intriguing surprise: the performance of cereals on organic farms

The great variability in the performance of cereals on organic farms that we have highlighted from past research trials has been confirmed in a new and more widely based trial. Participation from 20 producers gives the results a robust character and has enabled us to spot something we had not previously noted. EFRC researchers Prof Martin Wolfe AND Kay Hinchsliffe set out the results. Introduction EFRC is currently working on a Defra-funded project designed to use participatory research and development methodology, and is conducted on sites across the country with the participation of 20 farmers, seed producers and more than 10 researchers (EFRC, NIAB, Middlesex University, University of Kingston & HDRA). The idea is to integrate the contributions of different stakeholders into developing a robust system for identifying, testing, multiplying and marketing cereal varieties, lines, mixtures, and populations best suited to organic production in different parts of the country . Three high quality winter wheat varieties, Hereward, Solstice and Xi 19 and their mixture, were selected for the trial based on their performance in previous years’ replicated variety trials. Participating farmers drilled each variety in strips (total area of 1/10 ha) surrounded by their own winter wheat crop. This article summarises data from the first year of field trials (2003-4); since this is the first year they should be treated with caution. The trial is being repeated and has already been planted by essentially the same group of participating farmers

Effect of vetch wheat mixture and broccoli as preceding crops on organic summer vegetables: on farm trial in western Turkey

Organic farming requires the use of practices such as crop rotation, green manure and compost application instead of chemical compounds to enhance farm productivity. In this study, effects of two pre-crops (vetch-wheat mixture and broccoli) and additional fertilization (AF) strategy (compost and commercial fertilizer) were tested on organic production of two main crops (tomato and zucchini) and on soil fertility. The main aim of this on-farm trial is to evaluate the applicability of the results obtained over four years study under experimental conditions. Pre-crops and AF strategy had no significant effect on zucchini yield; highest tomato yield was recorded after vetch-wheat mixture and AF. At the end of the cycle soil organic matter statistically increased in vetch-wheat mixture with AF plots. Soil nitrogen (N) levels increased slightly in all treatments but this increase was not significantly different from the initial level of N. Vetch-wheat mixture and tomato rotation with AF provided the highest gross-margin due to a higher yield

Experimental Quantum Coin Tossing

In this letter we present the first implementation of a quantum coin tossing protocol. This protocol belongs to a class of ``two-party'' cryptographic problems, where the communication partners distrust each other. As with a number of such two-party protocols, the best implementation of the quantum coin tossing requires qutrits. In this way, we have also performed the first complete quantum communication protocol with qutrits. In our experiment the two partners succeeded to remotely toss a row of coins using photons entangled in the orbital angular momentum. We also show the experimental bounds of a possible cheater and the ways of detecting him

Relative Grazing Preference, Herbage Yield, In Vitro Digestibility, and Other Comparisons Among Seven Perennial Grasses at Various Times of the Year in Southcentral Alaska

This report summarizes a two-year study of dairy cow grazing preference among seven perennial grasses at various times during the growing season conducted at the University of Alaska's Matanuska Research Farm (6l.6°N) near Palmer in southcentral Alaska. Other factors documented were herbage yields, digestibility (in vitro dry-matter disappearance =IVDMD), winterhardiness, and persistence of grasses. Grasses compared were three named cultivars released by this station: 'Polar' bromegrass (Bromus inermis Leyss. x B. pumpellianus Scribn.), 'Nugget' Kentucky bluegrass (Poa pratensis L.), and 'Arctared' red fescue (Festuca ruhra L.); 'Engmo' timothy (Phleumpratense L.) from northern Norway; 'Garrison' creeping foxtail (Alopecurus arundinaceus Poir.) selected in North Dakota; and two native Alaska grasses, Siberian wildrye (Elymus sihiricus L.) and arctic wheatgrass (Agropyron sericeum Hitchc.)