Influence of outlying values and variations between sampling days on reference ranges for clinical chemistry in budgerigars (Melopsittacus undulatus)

Reference ranges for clinical chemistry variables were established for 99 budgerigars sampled monthly for 12 months. The data from the repeated measurements were compiled to obtain the most reliable population-based reference range defined to be relevant for the population of budgerigars over the whole year. Outlying values were excluded by reference to the population-based reference range and to previously determined values from the same individual, following the guidelines of the International Federation of Clinical Chemistry. The exclusion of outliers significantly reduced the calculated reference ranges.