RANDOM EFFECT SELECTION IN GENERALISED LINEAR MODELS: A PRACTICAL APPLICATION TO SLAUGHTERHOUSE SURVEILLANCE DATA INDENMARK

摘要

We analysed abattoir recordings of meat inspection codes with possible relevance to on-farm animal welfare in cattle. Random effects logistic regression models were used to describe individual-level data obtained from 461,406 cattle slaughtered in Denmark. Our results demonstrate that the largest variance partition was at farm level for most codes, but there was substantial variation in reporting for some meat inspection codes between abattoirs. There was also substantial agreement for the relative under or over-reporting of different slaughter codes within individual abattoirs. This indicates that the sensitivity of routine surveillance in Denmark is affected by differences in the working practices between abattoirs, resulting in biased prevalenceestimates. Therefore, it is essential to correct for the variation in reporting between abattoirs before meaningful inference can be made from prevalence estimates based on data derived from meat inspection.