Solving clustering as ill-posed problem: experiments with K-Means algorithm
This is an incremental improvement for clustering in neuroscience data analysis.
The paper tackles clustering as an ill-posed inverse problem by applying PCA with feature selection methods to the K-Means algorithm, finding that Wishart criteria reduce matrix condition number and align with a theorem linking clusters to PCA components in fMRI data.
In this contribution, the clustering procedure based on K-Means algorithm is studied as an inverse problem, which is a special case of the illposed problems. The attempts to improve the quality of the clustering inverse problem drive to reduce the input data via Principal Component Analysis (PCA). Since there exists a theorem by Ding and He that links the cardinality of the optimal clusters found with K-Means and the cardinality of the selected informative PCA components, the computational experiments tested the theorem between two quantitative features selection methods: Kaiser criteria (based on imperative decision) versus Wishart criteria (based on random matrix theory). The results suggested that PCA reduction with features selection by Wishart criteria leads to a low matrix condition number and satisfies the relation between clusters and components predicts by the theorem. The data used for the computations are from a neuroscientific repository: it regards healthy and young subjects that performed a task-oriented functional Magnetic Resonance Imaging (fMRI) paradigm.