R Coding Challenge: How many Lockers are Open?


The German news magazine DER SPIEGEL has a regular puzzle section in its online version, called “Rätsel der Woche” (“Riddle of the Week”). Some of those puzzles are quite interesting but I am often too lazy to solve them analytically.

So I often kill two birds with one stone: having fun solving the puzzle with R and creating some new teaching material for my R classes! This is what we will do with one of those more interesting riddles, which is quite hard to solve analytically but relatively easy to solve with R, so read on!
Continue reading “R Coding Challenge: How many Lockers are Open?”

ELIZA Chatbot in R: Build Yourself a Shrink


More and more companies use chatbots for engaging with their customers. Often the underlying technology is not too sophisticated, yet many people are stunned at how human-like those bots can appear. The earliest example of this was an early natural language processing (NLP) computer program called Eliza created 1966 at the MIT Artificial Intelligence Laboratory by Professor Joseph Weizenbaum.

Eliza was supposed to simulate a psychotherapist and was mainly created as a method to show the superficiality of communication between man and machine. Weizenbaum was surprised by the number of individuals who attributed human-like feelings to the computer program, including his own secretary!

If you want to build a simple Eliza-like chatbot yourself with R read on!
Continue reading “ELIZA Chatbot in R: Build Yourself a Shrink”

Create Return Triangle Plots with R


How lucrative stocks are in the long run is not only dependent on the length of the investment period but even more on the actual date the investment starts and ends!

Return Triangle Plots are a great way to visualize this phenomenon. If you want to learn more about them and how to create them with R read on!
Continue reading “Create Return Triangle Plots with R”

Why Gradient Descent Works (and How To Animate 3D-Functions in R)


The workhorse of Machine Learning is Gradient Descent. If you want to understand how and why it works and, along the way, want to learn how to plot and animate 3D-functions in R read on!
Continue reading “Why Gradient Descent Works (and How To Animate 3D-Functions in R)”

COVID-19 vaccine “95% effective”: It doesn’t mean what you think it means!


COVID-19 has the world more than ever in its grip – but there is hope: several vaccines have been developed which promise to deliver “95% efficacy”.

When people read this many assume that it means that 95% of vaccinated persons will be protected from infection – but that is not true. Even many (science) journalists get it wrong! If you want to understand what it really means, read on!
Continue reading “COVID-19 vaccine “95% effective”: It doesn’t mean what you think it means!”

OneR in Medical Research: Finding Leading Symptoms, Main Predictors and Cut-Off Points


We already had a lot of examples that make use of the OneR package (install free from CRAN), which can be found in the respective Category: OneR.

Here we will give you some concrete examples from the area of research on Type 2 Diabetes Mellitus (DM) to show that the package is especially well suited in the field of medical research, so read on!
Continue reading “OneR in Medical Research: Finding Leading Symptoms, Main Predictors and Cut-Off Points”

Logistic Regression as the Smallest Possible Neural Network


We already covered Neural Networks and Logistic Regression in this blog.

If you want to gain an even deeper understanding of the fascinating connection between those two popular machine learning techniques read on!
Continue reading “Logistic Regression as the Smallest Possible Neural Network”

xkcd Comics as a Minimal Example for Calling APIs, Downloading Files and Displaying PNG Images with R


xkcd webcomics is one of the institutions of the internet, especially for the nerd community. If you want to learn how to fetch JSON data from a REST API, download a file from the internet and display a PNG file in a ultra-simple example, read on!
Continue readingxkcd Comics as a Minimal Example for Calling APIs, Downloading Files and Displaying PNG Images with R”

How to Catch a Thief: Unmasking Madoff’s Ponzi Scheme with Benford’s Law

One of my starting points into quantitative finance was Bernie Madoff’s fund. Back then because Bernie was in desperate need of money to keep his Ponzi scheme running there existed several so-called feeder funds.

One of them happened to approach me to offer me a once-in-a-lifetime investment opportunity. Or so it seemed. Now, there is this old saying that when something seems too good to be true it probably is. If you want to learn what Benford’s law is and how to apply it to uncover fraud, read on!
Continue reading “How to Catch a Thief: Unmasking Madoff’s Ponzi Scheme with Benford’s Law”