Ramblings about statistics, AI, and psychology.

  • Confidence Intervals for Noncentrality Parameters

    In recent years, it has become a notion to not only report point estimates of effect sizes, but also confidence intervals for said effect sizes. I have created a small R script to calculate the bounds of such a confidence interval in the case of t- and F-distributions. 

  • Differences in Pollster Predictions

    Differences in Pollster Predictions

    The New York Times published an interesting piece on the differences between pollsters’ predictions. All five predictions used the same data set, so sampling differences are not of concern. Still, there was a difference of up to 5% between the predictions. 

  • Michael Inzlicht on loosing faith in science

    Michael Inzlicht on loosing faith in science

    Michael Inzlicht has posted an article on his blog about how he lost faith in psychological science after reading the now infamous paper on “false-positive psychology”. It is interesting for me to note that my experience is somewhat different.

  • Fraud in Medical Research

    Already in September last year, Der Spiegel published an interview with Peter Wilmshurst, a British medical doctor and whistleblower who made fraudulent practices in medical research public. A very interesting article that’s worth reading.

  • The Vanual: Customizing a Van for a Mobile Lifestyle

    The Vanual: Customizing a Van for a Mobile Lifestyle

    While sitting in one of my three offices, dreaming of beautiful, exotic and serene places is just natural. Zach Both does not dream about these places, he just goes there. But he is not a travel-a-my-life type of guy, but a film maker and designer who happens to life mobile: He customized a van to…

  • Euro Cup predictions through Stan

    Euro Cup predictions through Stan

    After I calculated the probabilities of Germany dropping out of the world cup two years ago, I always wanted to do some Bayesian modeling for the Bundesliga or the Euro Cup that started yesterday. Unfortunately, I never came to it. But Andrew Gelman posted some model by Leonardo Egidi today on his blog: Leonardo Egidi…

  • Choosing Cut-Offs in Tests

    Choosing Cut-Offs in Tests

    My last blog post was on the difference between Sensitivity, Specificity and the Positive Predictive Value. While showing that a positive test result can represent a low probability of actually having a trait or a disease, this example used the values of Sensitivity and Specificity as pre-known input. For established tests and measures they indeed…

  • Visualizing Sensitivity and Specificity of a Test

    In my university course on Psychological Assessment, I recently explained the different quality criteria of a test used for dichotomous decisions (yes/no, positive/negative, healthy/sick, …). A quite popular example in textbooks is the case of cancer screenings, where an untrained reader might be surprised by the low predictive value of a test. I created a…

  • Serengeti Park

    Serengeti Park

    Today, I don’t have cherry blossoms for you. Just some animals from the Serengeti Park. You can find higher resolutions at my 500px profile.

  • Vagrant VM for starting a Rails project

    This is something off-topic for this blog, but after spending several hours setting up an environment for developing and testing a Ruby on Rails project, I’d like to share my solution. I recently had an idea for a small web-project, for that I’d like to use Ruby on Rails. From previous attempts of using Rails,…

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