Learning R: Painting with Fire


A few months ago I published a post on recursion: To understand Recursion you have to understand Recursion…. In this post we will see how to use recursion to fill free areas of an image with colour, the caveats of recursion and how to transform a recursive algorithm into a loop-based version using a queue – so read on…
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Learning R: The Ultimate Introduction (incl. Machine Learning!)


There are a million reasons to learn R (see e.g. Why R for Data Science – and not Python?), but where to start? I present to you the ultimate introduction to bring you up to speed! So read on…
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Was the Bavarian Abitur too hard this time?


Bavaria is known for its famous Oktoberfest… and within Germany also for its presumably difficult Abitur, a qualification granted by university-preparatory schools in Germany.

A mandatory part for all students is maths. This year many students protested that the maths part was way too hard, they even started an online petition with more than seventy thousand supporters at this time of writing!

It is not clear yet whether their marks will be adjusted upwards, the ministry of education is investigating the case. As a professor in Bavaria who also teaches statistics I will take the opportunity to share with you an actual question from the original examination with solution, so read on…
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Backtest Trading Strategies Like a Real Quant


R is one of the best choices when it comes to quantitative finance. Here we will show you how to load financial data, plot charts and give you a step-by-step template to backtest trading strategies. So, read on…
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The Rich didn’t earn their Wealth, they just got Lucky


Tomorrow, on the First of May, many countries celebrate the so called International Workers’ Day (or Labour Day): time to talk about the unequal distribution of wealth again, so read on!
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Google’s Eigenvector… or: How a Random Surfer Finds the Most Relevant Webpages


Like most people, you will have used a search engine lately, like Google. But have you ever thought about how it manages to give you the most fitting results? How does it order the results so that the best are on top? Read on to find out!
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Base Rate Fallacy – or why No One is justified to believe that Jesus rose


In this post we are talking about one of the most unintuitive results in statistics: the so called false positive paradox which is an example of the so called base rate fallacy. It describes a situation where a positive test result of a very sensitive medical test shows that you have the respective disease… yet you are most probably healthy!
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Separating the Signal from the Noise: Robust Statistics for Pedestrians


One of the problems of navigating an autonomous car through a city is to extract robust signals in the face of all the noise that is present in the different sensors. Just taking something like an arithmetic mean of all the data points could possibly end in a catastrophe: if a part of a wall looks similar to the street and the algorithm calculates an average trajectory of the two this would end in leaving the road and possibly crashing into pedestrians. So we need some robust algorithm to get rid of the noise. The area of statistics that especially deals with such problems is called robust statistics and the methods used therein robust estimation.
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Symbolic Regression, Genetic Programming… or if Kepler had R


A few weeks ago we published a post about using the power of the evolutionary method for optimization (see Evolution works!). In this post we will go a step further, so read on…
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Inverse Statistics – and how to create Gain-Loss Asymmetry plots in R


Asset returns have certain statistical properties, also called stylized facts. Important ones are:

  • Absence of autocorrelation: basically the direction of the return of one day doesn’t tell you anything useful about the direction of the next day.
  • Fat tails: returns are not normal, i.e. there are many more extreme events than there would be if returns were normal.
  • Volatility clustering: basically financial markets exhibit high-volatility and low-volatility regimes.
  • Leverage effect: high-volatility regimes tend to coincide with falling prices and vice versa.

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