Author: Alexej's blog

[Redirects to the 0-fold Cross Validation blog – my new math/stats/ML focused blog.] I can’t count how many times I have looked up the formal (measure theoretic) definitions of conditional...continue reading.

For a while now I wanted to migrate my websites away from Github pages. While Github provides an excellent free service, there are some limitations to its capabilities, and the...continue reading.

Last month, after mentioning “deep learning” a few times to some professors, I suddenly found myself in a position where I had to prepare three talks about “deep learning” within...continue reading.

Unfortunately this was not taught in any of my statistics or data analysis classes at university (wtf it so needs to be :scream_cat:). So it took me some time until...continue reading.

The United States Patent and Trademark office (USPTO) provides immense amounts of data (the data I used are in the form of XML files). After coming across these datasets, I...continue reading.

Recently I came across the classical 1983 paper A note on screening regression equations by David Freedman. Freedman shows in an impressive way the dangers of data reuse in statistical...continue reading.

A reviewer asked me to report detailed running times for all (so many :scream:) performed computations in one of my papers, and so I spent a Saturday morning figuring out...continue reading.

The lean startup methodology consists of a set of principles that were proposed and popularized by Eric Ries in the book The Lean Startup (and elsewhere). He believes that startup...continue reading.

Based on an interesting dataset from the Wall Street Journal I made the above visualization of the median starting salary for US college graduates from different undergraduate institutions (I have...continue reading.

In many applications, data naturally form an n-way tensor with n > 2, rather than a “tidy” table. As mentioned in the beginning of my last blog post, a tensor...continue reading.

A tensor is essentially a multi-dimensional array: a tensor of order one is a vector, which simply is a column of numbers, a tensor of order two is a matrix,...continue reading.

I think that it doesn’t matter what operating system you use — as long as you know your OS of choice well!:bowtie: This is a Linux command cheat sheet covering...continue reading.

Many statistical modeling problems reduce to a minimization problem of the general form: or where is some type of loss function, denotes the data, and is a penalty, also referred...continue reading.

Lately I notice a sharp increase in my coffee consumption (reading Howard Schultz’s Starbucks book, which is actually quite good by the way, does not help either :grimacing:). Having recently...continue reading.

Lately I was getting a little bored with genomic data (and then TCGA2STAT started to give me a segfault on my university’s high performance computing facility too :stuck_out_tongue:). So I...continue reading.

This weekend I have set up an old laptop with a broken screen as an Amahi server in my house, such that I can access the files stored on the...continue reading.

As a grad student working primarily on statistical methodology, I regularly experience phases of total disillusionment with math/stats. Recently I realized that when I don’t feel like doing “real” math...continue reading.

I have always found the common definition of the generalized inverse of a matrix quite unsatisfactory, because it is usually defined by a mere property, , which does not really...continue reading.

I had some fun analysing the shelter animal data from kaggle using the Ruby gems daru for data wrangling and statsample-glm for model fitting. In this blog post, I want...continue reading.

This blog post demonstrates the usage of the R package dplyr. It turns out that dplyr is intuitive to the point where I probably won’t ever need to look back...continue reading.