# distance measure

1. ### Deriving the Mahalanobis distance formula, where is the mistake in my reasoning?

The squared Mahalanobis distance/length of an observation vector x from its mean (assuming its the zero vector) is given by x^T * S^-1 * x S is the covariance matrix for any given observation x. x^T is the transpose of x This is my reasoning for how its derived. The covariance matrix S is...
2. ### Distance Measures, High Dimensions

Hi all, I am learning how to handle high dimensional data. I am trying to cluster a matrix, that is about 2000×5000, with log-likelihood values in its cells. As a first step, to be able to visualize my data, I used Principal Component Analysis (PCA) and Principal Coordinate Analysis (PCoA). As...
3. ### similarity between two random variables

There have two random variables, each of which is of five dimension. One random variable tracks the data collected from one device. The other random variable represents the data collected from another device. I would like to see whether these two devices are replaceable with each other by...
4. ### Distance measures in cluster analysis

Hi, I conducted a k-means cluster analysis, which included each person's Euclidean distance from the centroid of his/her assigned cluster. Is there a way to calculate each person's distance from the centroid of a DIFFERENT cluster than his/her assigned cluster? In other words, if a person...
5. ### PERMANOVA - choice of distance measure

Hi, I want to run a (PRIMER based) PERMANOVA analysis on my univariate data (output var.= weight of organisms, and 3 factors = 2 fixed, 1 random) and I'm wondering which distance measure (Bray-Curtis or Euclidean distance) to use to create the resemblance matrix. In most literature that I...