7,709 research outputs found
The detection of cheating in multiple choice examinations
Cheating in examinations is acknowledged by an increasing number of
organizations to be widespread. We examine two different approaches to assess
their effectiveness at detecting anomalous results, suggestive of collusion,
using data taken from a number of multiple-choice examinations organized by the
UK Radio Communication Foundation. Analysis of student pair overlaps of correct
answers is shown to give results consistent with more orthodox statistical
correlations for which confidence limits as opposed to the less familiar
"Bonferroni method" can be used. A simulation approach is also developed which
confirms the interpretation of the empirical approach.Comment: 16 pages, 13 figure
Deciphering the fluctuations of high frequency birth rates
Here the term "high frequency" refers to daily, weekly or monthly birth data.
The fluctuations of daily birth numbers show a succession of spikes and dips
which, at least at first sight, looks almost as random as white noise. However
in recent times several studies were published, including by the present
authors, which have given better insight into how birth is affected by
exogenous factors. One of them concerns the way adverse conditions (e.g.
famines, diseases, earthquakes, heat waves) temporarily affect the conception
capacity of populations, thus producing birth rate troughs 9 months after
mortality waves. In addition, religious interdicts (e.g. during the Lent
period) lead to reduced conceptions. These as well as other effects raise the
hope that we will soon be able to "read" and interpret birth rate patterns just
as the Egyptologist Jean-Francois Champollion managed to decipher many (though
not all) hieroglyphs.Comment: 23 pages, 10 figure
The physics of large-scale food crises
Investigating the ``physics'' of food crises consists in identifying features
which are common to all large-scale food crises. One element which stands out
is the fact that during a food crisis there is not only a surge in deaths but
also a correlative temporary decline in conceptions and subsequent births. As a
matter of fact, birth reduction may even start several months before the death
surge and can therefore serve as an early warning signal of an impending
crisis. This scenario is studied in three cases of large-scale food crises.
Finland (1868), India (1867--1907), China (1960--1961). It turns out that
between the regional amplitudes of death spikes and birth troughs there is a
power law relationship. This confirms what was already observed for the
epidemic of 1918 in the United States (Richmond et al. 2018b). In a second part
of the paper we explain how this relationship can be used for the investigation
of mass-mortality episodes in cases where direct death data are either
uncertain or nonexistent.Comment: 29 pages, 11 figure
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