Determination of Outlier in Live-Weight performance data of Japanese Quails (Coturnix coturnix japonica) by Dffits and Cook’s Distance

Abstract

The data on live weight performance usually show a normal distribution. On the other hand, the majority of the statistical analysis methods have been developed on the basis of the assumption that the data under consideration are normally distributed. From time to time, in the analysis of the obtained numerical values, one or more observation is found to be quite far away from other observations. Such values are named as extreme value, deviated value, and outlier value. This study has been carried out by using Cook's distance and DFFITS criteria, with intent to determine the outliers of the live weight performance data of the Japanese quails, which has been classified according to their sex and have grown until the age of 70 days (10 weeks). In conclusion, it can be said that the DFFITS values are higher than COOK’s distance in male, female, and flock total. DFFITS method is a method that finds more outlier values when compared to COOK’s distance method in terms of finding outlier. DFFITS method should be used if precision is wanted to be enhanced, and COOK’s distance method should be preferred in less precision studies.