  The present study defines a new statistic for detecting laboratory effects in
the analysis of ordinal variation (ORDANOVA). The ORDANOVA is an analysis
method similar to one-way analysis of variance for analysing ordinal data
obtained from interlaboratory comparison studies. In this paper, we present an
approximate continuous distribution for the new statistic for the case of an
arbitrary number of ordinal levels, and we demonstrate that $alpha$-percentiles
of the distribution are suitable criteria for conducting statistical tests. In
addition, a real example involving data from an interlaboratory comparison
study is analysed using the proposed statistic.
