Analysis of Measurement Precision Experiment with Ordinal Categorical Variables

Many collaborative studies are run to evaluate precision of measurement methods. The main focus is on estimating repeatability and reproducibility, which are the variation within a laboratory and the overall variation of the measurement method, respectively. ISO 5725 provides how to design and analyze such precision experiments for quantitative cases where the measurement results follow a continuous distribution, namely a normal distribution. However, there are cases where the measurement results are qualitative such as binary or categorical. In this paper, the cases with ordinal categorical variables are considered. Using methods that can be applied to qualitative data, an analysis of a measurement precision experiment with measurements involving ordinal categorical variables is investigated. The data analysed are from an actual precision experiment of intratracheal administration testing whose objectives were to study the precision of a standardized test method for evaluating nanomaterial pulmonary toxicity.