Aug 9, 2013 — The Gap Statistic — The gap statistic is a method for approximating the “correct” number of clusters, k, for an unsupervised clustering. We do this by assessing a metric of error (the within cluster sum of squares) with regard to our choice of k.... Read more

Aug 6, 2013 — Segmentation of MRI with Bayesian Methods — Let’s say that I am a proponent of the idea that I can segment the brain into meaningful regions (e.g., caudate, amygdala, hippocampus…), which some may think is akin to cutting up the United States into said states.  This could... Read more

Aug 4, 2013 — Dimensionality Estimation of ICA with Bayesian Analysis — Across methods of matrix decomposition (ICA, Archetypal Analysis, NNMF), we run into the problem of needing to know how many signals to decompose our data to.  This is called model order selection.  If we choose a number that is too... Read more

Aug 3, 2013 — Mutual Information for Image Registration — Mutual information is an important concept for medical imaging, because it is so prominently used in image registration.  Let’s set up a typical registration problem.  Here we have two pictures of something that you see everyday, a dancing pickle! I’ve... Read more