3,172 research outputs found
Surrogate data for non-stationary signals
Standard tests for nonlinearity reject the null hypothesis of a Gaussian
linear process whenever the data is non-stationary. Thus, they are not
appropriate to distinguish nonlinearity from non-stationarity. We address the
problem of generating proper surrogate data corresponding to the null
hypothesis of an ARMA process with slowly varying coefficients.Comment: 4 pages, 4 figures. proceeding for a poste
Surrogate time series
Before we apply nonlinear techniques, for example those inspired by chaos
theory, to dynamical phenomena occurring in nature, it is necessary to first
ask if the use of such advanced techniques is justified "by the data". While
many processes in nature seem very unlikely a priori to be linear, the possible
nonlinear nature might not be evident in specific aspects of their dynamics.
The method of surrogate data has become a very popular tool to address such a
question. However, while it was meant to provide a statistically rigorous,
foolproof framework, some limitations and caveats have shown up in its
practical use. In this paper, recent efforts to understand the caveats, avoid
the pitfalls, and to overcome some of the limitations, are reviewed and
augmented by new material. In particular, we will discuss specific as well as
more general approaches to constrained randomisation, providing a full range of
examples. New algorithms will be introduced for unevenly sampled and
multivariate data and for surrogate spike trains. The main limitation, which
lies in the interpretability of the test results, will be illustrated through
instructive case studies. We will also discuss some implementational aspects of
the realisation of these methods in the TISEAN
(http://www.mpipks-dresden.mpg.de/~tisean) software package.Comment: 28 pages, 23 figures, software at
http://www.mpipks-dresden.mpg.de/~tisea
FolkRank: A Ranking Algorithm for Folksonomies
In social bookmark tools users are setting up lightweight conceptual structures called folksonomies. Currently, the information retrieval support is limited. We present a formal model and a new search algorithm for folksonomies, called FolkRank, that exploits the structure of the folksonomy. The proposed algorithm is also applied to find communities within the folksonomy and is used to structure search results. All findings are demonstrated on a large scale dataset. A long version of this paper has been published at the European Semantic Web Conference 2006
Cognitive Abilities and Behavioral Biases
We use a simple, three-item test for cognitive abilities to investigate whether established behavioral biases that play a prominent role in behavioral economics and finance are related to cognitive abilities. We find that higher test scores on the Cognitive Reflection Test of Frederick (2005) indeed are correlated with lower incidences of the conjunction fallacy, conservatism in updating probabilities, and overconfidence. Test scores are also significantly related to subjects’ time and risk preferences. We find no influence on anchoring. However, even if biases are lower for people with higher cognitive abilities, they still remain substantial.cognitive reflection test, behavioral finance, biases, cognitive abilities
Cooling-Off in Negotiations - Does It Work?
Negotiations frequently end in conflict after one party rejects a final offer. In a large-scale internet experiment, we investigate whether a 24-hour coolingoff period leads to fewer rejections in ultimatum bargaining. We conduct a standard cash treatment and a lottery treatment, where subjects receive lottery tickets for several large prizes - emulating a high-stakes environment. In the lottery treatment, unfair offers are less frequently rejected, and cooling-off significantly reduces the rejection rate further. In the cash treatment, rejections are more frequent and remain so after cooling-off. This treatment difference is particularly pronounced for subjects with lower cognitive abilities.
Cognitive Abilities and Behavioral Biases
We use a simple, three-item test for cognitive abilities to investigate whether established behavioral biases that play a prominent role in behavioral economics and finance are related to cognitive abilities. We find that higher test scores on the Cognitive Reflection Test of Frederick (2005) indeed are correlated with lower incidences of the conjunction fallacy, conservatism in updating probabilities, and overconfidence. Test scores are also significantly related to subjects' time and risk preferences. We find no influence on anchoring. However, even if biases are lower for people with higher cognitive abilities, they still remain substantial.
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