A Study on Determination of Outlier Observations by Using Chi-Square Threshold Value

Authors : Fahrettin KAYA, Esra YAVUZ, Şeyma KOÇ, Ömer Faruk KARAOKUR

Pages : 7-10

View : 23 | Download : 9

Publication Date : 2019-01-01

Article Type : Research Paper

Abstract :Outlier observations are observations that are out of the tendency of all observations in a data set. The observations come out in situations such as faulty observation, incorrect data entry. It is important to be able to identify these observations as the results of statistical analysis, for example such as multiple regression analysis, can be quite sensitive against to these observations. Outlier observations are mostly determined by using distance calculation, statistical test and density based approaches. In this study, the distances of each observation vector to the center were calculated with Mahalanobis distance by using R program. For this purpose, the features such as hematokrit insert ignore into journalissuearticles values(htc);, hemoglobin insert ignore into journalissuearticles values(hgb);, mean platelet volume insert ignore into journalissuearticles values(mpv);, platelet distribution width insert ignore into journalissuearticles values(pdw);, nonbacterial prostatitis insert ignore into journalissuearticles values(nbp); and pulse pressure values measured in the blood of 315 heart patients were examined as data set. As a result of the research, sixteen observations were found as outlier observation. It is thought that the result of this study will help the researchers trying to find out especially the outlier observations.
Keywords : Outlier observation, Mahalanobis distance, Threshold value