Details

Autor(en) / Beteiligte

• Sguera, Carlo
• Galeano, Pedro
• Lillo, Rosa E

Titel

Functional outlier detection by a local depth with application to NO x levels

Ist Teil von

• Stochastic environmental research and risk assessment, 2016-04, Vol.30 (4), p.1115-1130

Erscheinungsjahr

2016

Quelle

Springer LINK 全文期刊数据库

Beschreibungen/Notizen

• (ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).This paper proposes methods to detect outliers in functional data sets and the task of identifying atypical curves is carried out using the recently proposed kernelized functional spatial depth (KFSD). KFSD is a local depth that can be used to order the curves of a sample from the most to the least central, and since outliers are usually among the least central curves, we present a probabilistic result which allows to select a threshold value for KFSD such that curves with depth values lower than the threshold are detected as outliers. Based on this result, we propose three new outlier detection procedures. The results of a simulation study show that our proposals generally outperform a battery of competitors. We apply our procedures to a real data set consisting in daily curves of emission levels of nitrogen oxides (NO...) since it is of interest to identify abnormal NO... levels to take necessary environmental political actions.