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This article in CS

  1. Vol. 45 No. 3, p. 1045-1051
     
    Received: May 13, 2004
    Published: May, 2005


    * Corresponding author(s): piepho@uni-hohenheim.de
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doi:10.2135/cropsci2004.0293

A Threshold Model for Multiyear Genebank Data Based on Different Rating Scales

  1. K. Hartung and
  2. H. P. Piepho *
  1. Institut für Pflanzenbau und Grünland (430c), Universität Hohenheim, Fruwirthstrasse 23, D-70593 Stuttgart, Germany

Abstract

Genebanks routinely assess plant characteristics of accessions on an ordinal rating scale. A common problem with long-term data is that the rating scale is changed from time to time. This paper proposes a method for joint analysis of data from different rating scales, assuming a threshold model with a common latent scale for the different rating systems. The method may be used to derive mean scores on any one of the rating scales based on a long-term series of evaluation trials, as is illustrated using evaluation data on barley (Hordeum spp.). While the proposed method was motivated by data problems encountered in genebanks, it may be of equal interest in other areas of application, such as plant breeding, where rating scales change across time.

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