Robust Clustering Method for the Detection of Outliers: Using AIC to Select the Number of Clusters

Santos-Pereira, Carla; Pires, Ana M.

doi:10.1007/978-3-642-34904-1_43

Cited by 2 publications

(1 citation statement)

References 13 publications

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“…However, the classical mean and covariance matrix in MD suffer from masking and swamping effects if the data contain outliers (Santos-pereira & Pires, 2013). Masking occurs when some of the outliers are left unidentified (false negative) and swamping occurs when inliers data are mistakenly identified as outliers (false positive) (Filzmoser & Todorov, 2013).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Robust Estimators’ Performance for Detecting Outliers in Multivariate Data

Mutalib

Satari

Yusoff

2021

JOSMA

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In multivariate data, outliers are difficult to detect especially when the dimension of the data increase. Mahalanobis distance (MD) has been one of the classical methods to detect outliers for multivariate data. However, the classical mean and covariance matrix in MD suffered from masking and swamping effects if the data contain outliers. Due to this problem, many studies used a robust estimator instead of the classical estimator of mean and covariance matrix. In this study, the performance of five robust estimators namely Fast Minimum Covariance Determinant (FMCD), Minimum Vector Variance (MVV), Covariance Matrix Equality (CME), Index Set Equality (ISE), and Test on Covariance (TOC) are investigated and compared. FMCD has been widely used and is known as among the best robust estimator. However, there are certain conditions that FMCD still lacks. MVV, CME, ISE and TOC are innovative of FMCD. These four robust estimators improve the last step of the FMCD algorithm. Hence, the objective of this study is to observe the performance of these five estimator to detect outliers in multivariate data particularly TOC as TOC is the latest robust estimator. Simulation studies are conducted for two outlier scenarios with various conditions. There are three performance measures, which are pout, pmask and pswamp used to measure the performance of the robust estimators. It is found that the TOC gives better performance in pswamp for most conditions. TOC gives better results for pout and pmask for certain conditions.

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Section: Introductionmentioning

confidence: 99%

Comparison of Robust Estimators’ Performance for Detecting Outliers in Multivariate Data

Mutalib

Satari

Yusoff

2021

JOSMA

View full text Add to dashboard Cite

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Secondary supermarket revolution: food sources and food security in Northern Namibia

Kazembe

Crush

2022

Urban Transform

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A central feature of the transformation of urban food systems in cities of the Global South is the growing presence of supermarkets and their supply chains, often termed supermarketization or a supermarket revolution. A key issue in the African context is whether supermarkets are a threat to other sources of food including informal sector vendors. Most research on the supermarket revolution and competition with other food retailers focuses on large urban conurbations with little attention paid to the role of supermarkets in smaller urban centres. This paper aims to rectify this situation through a case study of the role of supermarkets in three small urban centres in northern Namibia. The paper uses data from a representative household food security survey in 2018 which collected detailed information on household food consumption and food purchasing patterns. We show that supermarkets have established a dominant role in the local food system and are patronized by almost all households. However, the informal food sector displays considerable resilience and is patronized on a regular basis by low-income households. Future research on the impact of the secondary supermarket revolution should examine the experience and strategies of informal food vendors and whether the relationship with supermarkets is truly symbiotic or not.

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Robust Clustering Method for the Detection of Outliers: Using AIC to Select the Number of Clusters

Cited by 2 publications

References 13 publications

Comparison of Robust Estimators’ Performance for Detecting Outliers in Multivariate Data

Comparison of Robust Estimators’ Performance for Detecting Outliers in Multivariate Data

Secondary supermarket revolution: food sources and food security in Northern Namibia

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