36,877 research outputs found
What May Visualization Processes Optimize?
In this paper, we present an abstract model of visualization and inference
processes and describe an information-theoretic measure for optimizing such
processes. In order to obtain such an abstraction, we first examined six
classes of workflows in data analysis and visualization, and identified four
levels of typical visualization components, namely disseminative,
observational, analytical and model-developmental visualization. We noticed a
common phenomenon at different levels of visualization, that is, the
transformation of data spaces (referred to as alphabets) usually corresponds to
the reduction of maximal entropy along a workflow. Based on this observation,
we establish an information-theoretic measure of cost-benefit ratio that may be
used as a cost function for optimizing a data visualization process. To
demonstrate the validity of this measure, we examined a number of successful
visualization processes in the literature, and showed that the
information-theoretic measure can mathematically explain the advantages of such
processes over possible alternatives.Comment: 10 page
How to use the Kohonen algorithm to simultaneously analyse individuals in a survey
The Kohonen algorithm (SOM, Kohonen,1984, 1995) is a very powerful tool for
data analysis. It was originally designed to model organized connections
between some biological neural networks. It was also immediately considered as
a very good algorithm to realize vectorial quantization, and at the same time
pertinent classification, with nice properties for visualization. If the
individuals are described by quantitative variables (ratios, frequencies,
measurements, amounts, etc.), the straightforward application of the original
algorithm leads to build code vectors and to associate to each of them the
class of all the individuals which are more similar to this code-vector than to
the others. But, in case of individuals described by categorical (qualitative)
variables having a finite number of modalities (like in a survey), it is
necessary to define a specific algorithm. In this paper, we present a new
algorithm inspired by the SOM algorithm, which provides a simultaneous
classification of the individuals and of their modalities.Comment: Special issue ESANN 0
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