Assessing the repeatability and reproducibility of distortion product otoacoustic emissions in Sprague-Dawley rats by hierarchical modeling

We present how the repeatability and reproducibility of a measurement device can be estimated from a suitably defined hierarchical linear model. The methodology is illustrated using a collection of eight data sets which consist of the distortion product otoacoustic emission recordings collected from both ears of ten young Sprague-Dawley rats at different frequencies under eight different recording conditions. We formulate a model which extends the commonly used one-way random effects model (5) to account for an experimental setup that is more elaborated than the ones traditionally used in interlaboratory experiments. The fitted model is easily interpretable and furnishes as a by-product the frequencies at which the highest response level is achieved under the eight recording conditions. These values together with the repeatability and reproducibility limits of the protocols are crucial in contributing to the enhancement of the research capabilities on the possible causes of hearing impairment.