@article{SchneiderScheibler1983,
  author    = {Schneider, Wolfgang and Scheibler, D.},
  title     = {Probleme und M{\"o}glichkeiten bei der Bewertung von Clusteranalyse-Verfahren: II. Ergebnisse einer Monte-Carlo-Studie},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69637},
  year      = {1983},
  abstract  = {Ziel der vorliegenden Untersuchung war es, Aufschluß {\"u}ber die unterschiedliche Qualit{\"a}t hierarchischer und nicht-hierarchischer (partionierender) Clusteranalyseverfahren zu gewinnen. Die Reproduktionsg{\"u}te beider Clusteranalyse-Varianten wurde anhand von 200 Monte-Carlo-Datens{\"a}tzen (multivariat normalverteilte Mixturen) zu {\"u}berpr{\"u}fen versucht, wobei jeweils unterschiedliche Proportionen der Daten-Elemente klassifiZiert werden mußten. Es zeigte sich, daß insgesamt gesehen die hierarchischen Algorithmen nach WARD und LANCE-WILUAMS am besten dazu in der Lage waren, die vorgegebenen Datenstrukturen zu reproduzieren, andererseits aber die herangezogenen partitionierenden KMEANS-Verfahren nicht schlechter abschnitten, wenn die L{\"o}sung der WARD-Technik als Start-Partition vorgegeben wurde.},
  subject      = {Monte-Carlo-Simulation},
  language  = {de}
}
@article{ChipperfieldDythamHovestadt2011,
  author    = {Chipperfield, Joseph D. and Dytham, Calvin and Hovestadt, Thomas},
  title     = {An Updated Algorithm for the Generation of Neutral Landscapes by Spectral Synthesis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68938},
  year      = {2011},
  abstract  = {Background: Patterns that arise from an ecological process can be driven as much from the landscape over which the process is run as it is by some intrinsic properties of the process itself. The disentanglement of these effects is aided if it possible to run models of the process over artificial landscapes with controllable spatial properties. A number of different methods for the generation of so-called 'neutral landscapes' have been developed to provide just such a tool. Of these methods, a particular class that simulate fractional Brownian motion have shown particular promise. The existing methods of simulating fractional Brownian motion suffer from a number of problems however: they are often not easily generalisable to an arbitrary number of dimensions and produce outputs that can exhibit some undesirable artefacts. Methodology: We describe here an updated algorithm for the generation of neutral landscapes by fractional Brownian motion that do not display such undesirable properties. Using Monte Carlo simulation we assess the anisotropic properties of landscapes generated using the new algorithm described in this paper and compare it against a popular benchmark algorithm. Conclusion/Significance: The results show that the existing algorithm creates landscapes with values strongly correlated in the diagonal direction and that the new algorithm presented here corrects this artefact. A number of extensions of the algorithm described here are also highlighted: we describe how the algorithm can be employed to generate landscapes that display different properties in different dimensions and how they can be combined with an environmental gradient to produce landscapes that combine environmental variation at the local and macro scales.},
  subject      = {Landschaft},
  language  = {en}
}