Current Volume | Browse | Search | RSSHome | Instructions for Authors | LaTeX Style Files | Editorial Board

Authors: Stefanie Jachner, K. Gerald van den Boogaart, Thomas Petzoldt
Title: [download]
(2379)
Statistical Methods for the Qualitative Assessment of Dynamic Models with Time Delay (R Package qualV)
Reference: Vol. 22, Issue 8, Sep 2007
Submitted 2007-02-26, Accepted 2007-06-25
Type: Article
Abstract:

Results of ecological models differ, to some extent, more from measured data than from empirical knowledge. Existing techniques for validation based on quantitative assessments sometimes cause an underestimation of the performance of models due to time shifts, accelerations and delays or systematic differences between measurement and simulation. However, for the application of such models it is often more important to reproduce essential patterns instead of seemingly exact numerical values. This paper presents techniques to identify patterns and numerical methods to measure the consistency of patterns between observations and model results. An orthogonal set of deviance measures for absolute, relative and ordinal scale was compiled to provide informations about the type of difference. Furthermore, two different approaches accounting for time shifts were presented. The first one transforms the time to take time delays and speed differences into account. The second one describes known qualitative criteria dividing time series into interval units in accordance to their main features. The methods differ in their basic concepts and in the form of the resulting criteria. Both approaches and the deviance measures discussed are implemented in an R package. All methods are demonstrated by means of water quality measurements and simulation data. The proposed quality criteria allow to recognize systematic differences and time shifts between time series and to conclude about the quantitative and qualitative similarity of patterns.

Paper: [download]
(2379)
Statistical Methods for the Qualitative Assessment of Dynamic Models with Time Delay (R Package qualV)
(application/pdf, 632.9 KB)
Supplements: [download]
(1023)
qualV_0.2-2.tar.gz: R source package
(application/x-gzip, 24.4 KB)
[download]
(1049)
v22i08.R: R example code from the paper
(application/zip, 630 Bytes)
Resources: BibTeX | OAI
Creative Commons License
This work is licensed under the licenses
Paper: Creative Commons Attribution 3.0 Unported License
Code: Commons GNU General Public License License
Current Volume | Browse | Search | RSSHome | Instructions for Authors | LaTeX Style Files | Editorial Board