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Detecting Spatial Outliers: the Role of the Local Influence Function

Giuseppe Arbia, Vincenzo Nardelli

arXiv 23 Oct 2024 · Statistics — Methodology

arXiv:2410.18261 · PDF · DOI · OpenAlex · Extracted main text

Abstract

In the analysis of large spatial datasets, identifying and treating spatial outliers is essential for accurately interpreting geographical phenomena. While spatial correlation measures, particularly Local Indicators of Spatial Association (LISA), are widely used to detect spatial patterns, the presence of abnormal observations frequently distorts the landscape and conceals critical spatial relationships. These outliers can significantly impact analysis due to the inherent spatial dependencies present in the data. Traditional influence function (IF) methodologies, commonly used in statistical analysis to measure the impact of individual observations, are not directly applicable in the spatial context because the influence of an observation is determined not only by its own value but also by its spatial location, its connections with neighboring regions, and the values of those neighboring observations. In this paper, we introduce a local version of the influence function (LIF) that accounts for these spatial dependencies. Through the analysis of both simulated and real-world datasets, we demonstrate how the LIF provides a more nuanced and accurate detection of spatial outliers compared to traditional LISA measures and local impact assessments, improving our understanding of spatial patterns.

Citation extraction

9
references
14
in-text mentions
9
distinct cited
1
self-citations
4,830
main-text words

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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Nardelli, V. and G. Arbia (2024) On robust measures of spatial correlation self0.87452100%
2Hampel, F. R (1974) The influence curve and its role in robust estimation0.64422100%
3Hampel, F. R., E. M. Ronchetti, P. J. Rousseeuw, and W. A. Stahel (1986) Robust Statistics: The Approach Based on Influence Functions0.40511100%
4Huber, P. J (1981) Robust Statistics0.40511100%
5Maronna, R. A., R. D. Martin, and V. J. Yohai (2006) Robust Statistics: Theory and Methods0.40511100%
6Anselin, L (1995) Local indicators of spatial association—lisa0.40511100%
7Moran, P. A (1950) Notes on continuous stochastic phenomena0.40511100%
8Pesaran, M. H. and C. F. Yang (2020) Econometric analysis of production networks with dominant units0.40511100%
9Rousseeuw, P. J. and A. M. Leroy (1897) Robust regression and outlier detection0.40511100%

Showing the top 9 of 9 scored citations.