6,717 research outputs found
Classical Business Cycles in America: Are National Business Cycles Synchronised?
This paper provides further evidence on the synchronization between business cycle regimes in seven American countries by using a classical business cycles approach. Despite recent increasing international economic transactions within this continent, our results suggest that national business cycles are largely idiosyncratic, except for the United States and Canada. Thus, international coordination of macroeconomic policies may not be effective, at least in the short-run. Also, as a by product, we find evidence of asymmetries between expansions and recessions in mean, volatility and duration in most countries.Business cycle regimes, international synchronization, North America, South America
The accuracy of farmer-generated data in an agricultural citizen science methodology.
Over the last decades, participatory approaches involving on-farm experimentation have become more prevalent in agricultural research. Nevertheless, these approaches remain difficult to scale because they usually require close attention from well-trained professionals. Novel large-N participatory trials, building on recent advances in citizen science and crowdsourcing methodologies, involve large numbers of participants and little researcher supervision. Reduced supervision may affect data quality, but the âWisdom of Crowdsâ principle implies that many independent observations from a diverse group of people often lead to highly accurate results when taken together. In this study, we test whether farmer-generated data in agricultural citizen science are good enough to generate valid statements about the research topic. We experimentally assess the accuracy of farmer observations in trials of crowdsourced crop variety selection that use triadic comparisons of technologies (tricot). At five sites in Honduras, 35 farmers (women and men) participated in tricot experiments. They ranked three varieties of common bean (Phaseolus vulgaris L.) for Plant vigor, Plant architecture, Pest resistance, and Disease resistance. Furthermore, with a simulation approach using the empirical data, we did an order-of-magnitude estimation of
the sample size of participants needed to produce relevant results. Reliability of farmersâ experimental observations was generally low (Kendallâs W0.174 to 0.676). But aggregated observations contained information and had sufficient validity (Kendallâs tau coefficient 0.33 to
0.76) to identify the correct ranking orders of varieties by fitting Mallows-Bradley-Terry models to the data. Our sample size simulation shows that low reliability can be compensated by engaging higher numbers of observers to generate statistically meaningful results, demonstrating the usefulness of the Wisdom of Crowds principle in agricultural research. In this first study on data quality from a farmer citizen science methodology, we show that realistic numbers of less than 200 participants can
produce meaningful results for agricultural research by tricot-style trials
Produccion y comercializacion de la larva de Rhynchophorus palmarum (Coleoptera : Dryophtoridae) en la Amazonia peruana
The effect of authority on the persuasiveness of mathematical arguments
Three experiments are reported which investigate the extent to which an authority figure
influences the level of persuasion undergraduate students and research-active mathematicians
invest in mathematical arguments. We demonstrate that, in some situations, both students and
researchers rate arguments as being more persuasive when they are associated with an expert
mathematician than when the author is anonymous. We develop a model which accounts for
these data by suggesting that, for both students and researchers, an authority figure only plays a
role when there is already some uncertainty about the argumentâs mathematical status.
Implications for pedagogy, and for future research, are discussed
How persuaded are you? A typology of responses
Several recent studies have suggested that there are two different ways in which a person
can proceed when assessing the persuasiveness of a mathematical argument: by
evaluating whether it is personally convincing, or by evaluating whether it is publicly
acceptable. In this paper, using Toulminâs (1958) argumentation scheme, we produce a
more detailed theoretical classification of the ways in which participants can interpret a
request to assess the persuasiveness of an argument. We suggest that there are (at least)
five ways in which such a question can be interpreted. The classification is illustrated
with data from a study that asked undergraduate students and research-active
mathematicians to rate how persuasive they found a given argument. We conclude by
arguing that researchers interested in mathematical conviction and proof validation need
to be aware of the different ways in which participants can interpret questions about the
persuasiveness of arguments, and that they must carefully control for these variations
during their studies
Semantic contamination and mathematical proof: can a non-proof prove?
The way words are used in natural language can influence how the same words are understood
by students in formal educational contexts. Hereweargue that this so-called semantic
contamination effect plays a role in determining how students engage with mathematical
proof, a fundamental aspect of learning mathematics. Analyses of responses to argument
evaluation tasks suggest that students may hold two different and contradictory conceptions
of proof: one related to conviction, and one to validity. We demonstrate that these
two conceptions can be preferentially elicited by making apparently irrelevant linguistic
changes to task instructions. After analyzing the occurrence of âproofâ and âproveâ in natural
language, we report two experiments that suggest that the noun form privileges evaluations
related to validity, and that the verb form privileges evaluations related to conviction.
In short, we show that (what is judged to be) a non-proof can sometimes (be judged to)
prove
Functional explanation in mathematics
Mathematical explanations are poorly understood. Although mathematicians seem to regularly suggest that some proofs are explanatory whereas others are not, none of the philosophical accounts of what such claims mean has become widely accepted. In this paper we explore Wilkenfeldâs (2014, Synthese, 191, 3367-3391) suggestion that explanations are those sorts of things that (in the right circumstances, and in the right manner) generate understanding. By considering a basic model of human cognitive architecture, we suggest that existing accounts of mathematical explanation are all derivable consequences of Wilkenfeldâs âfunctional explanationâ proposal. We therefore argue that the explanatory criteria offered by earlier accounts can all be thought of as features that make it more likely that a mathematical proof will generate understanding. On the functional account, features such as characterising properties, unification, and salience correlate with explanatoriness, but they do not define explanatoriness
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