Articles by FelixS

Optional stopping does not bias parameter estimates (if done correctly)

April 15, 2016 | FelixS

tl;dr: Optional stopping does not bias parameter estimates from a frequentist point of view if all studies are reported (i.e., no publication bias exists) and effect sizes are appropriately meta-analytically weighted. Several recent discussions on the Psychological Methods Facebook group surrounded the question whether an optional stopping procedure ... [Read more...]

A Compendium of Clean Graphs in R

March 12, 2015 | FelixS

[This is a guest post by Eric-Jan Wagenmakers and Quentin Gronau introducing the RGraphCompendium. Click here to see the full compendium!] Every data analyst knows that a good graph is worth a thousand words, and perhaps a hundred tables. But how should one create a good, clean graph? In R, ... [Read more...]

What does a Bayes factor feel like?

January 29, 2015 | FelixS

A Bayes factor (BF) is a statistical index that quantifies the evidence for a hypothesis, compared to an alternative hypothesis (for introductions to Bayes factors, see here, here or here). Although the BF is a continuous measure of evidence, humans love verbal labels, categories, and benchmarks. Labels give interpretations of ...
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Interactive exploration of a prior’s impact

February 21, 2014 | FelixS

The probably most frequent criticism of Bayesian statistics sounds something like “It’s all subjective – with the ‘right’ prior, you can get any result you want.”. In order to approach this criticism it has been suggested to do a sensitivity analysis (or robustness analysis), that demonstrates how the choice of ... [Read more...]

A short taxonomy of Bayes factors

January 21, 2014 | FelixS

I am starting to familiarize myself with Bayesian statistics. In this post I’ll show some insights I had concerning Bayes factors (BF). What are Bayes factors? Bayes factors provide a numerical value that quantifies how well a hypothesis predicts the empirical data relative to a competing hypothesis. For example, ... [Read more...]

Finally! Tracking CRAN packages downloads

June 11, 2013 | FelixS

[Update June 12: Data.tables functions have been improved (thanks to a comment by Matthew Dowle); for a similar approach see also Tal Galili's post] The guys from RStudio now provide CRAN download logs (see also this blog post). Great work! I always asked myself, how many people actually download my ... [Read more...]

At what sample size do correlations stabilize?

June 6, 2013 | FelixS

Maybe you have encountered this situation: you run a large-scale study over the internet, and out of curiosity, you frequently check the correlation between two variables. My experience with this practice is usually frustrating, as in small sample sizes (and we will see what “small” means in this context) correlations ... [Read more...]

Installation of WRS package (Wilcox’ Robust Statistics)

April 22, 2013 | FelixS

Some users had trouble installing the WRS package from R-Forge. Here’s a method that should work automatically and fail-safe: ?View Code RSPLUS# first: install dependent packages install.packages(c("MASS", "akima", "robustbase"))   # second: install suggested packages install.packages(c("cobs", "robust", "mgcv", "scatterplot3d", "quantreg", "rrcov", "lars", "pwr", "trimcluster", "... [Read more...]

Improved evolution of correlations

January 21, 2013 | FelixS

Update June 2013: A systematic analysis of the topic has been published:Schönbrodt, F. D., & Perugini, M. (2013). At what sample size do correlations stabilize? Journal of Research in Personality, 47, 609-612. doi:10.1016/j.jrp.2013.05.009 Check also the supplementary website, where you can find the PDF of the paper. As an update ... [Read more...]

Optimizing parameters for an oscillator – Video

January 10, 2013 | FelixS

Here’s a video how the modFit function from the FME package optimizes parameters for an oscillation. A Nelder-Mead-optimizer (R function optim) finds the best fitting parameters for an undampened oscillator. Minimum was found after 72 iterations, true parameter eta was -.05: Evolution of parameters in optimization process from Felix Schö... [Read more...]

R-package: Wilcox’ Robust Statistics updated (WRS v0.20)

January 8, 2013 | FelixS

Rand Wilcox constantly updates the functions accompanying his books on robust statistics. Recently, they have been updated to version 20. The functions are available in the WRS package for R – for installation simply type install.packages("WRS", repos="") In version 0.20, a number of functions dealing with ANCOVA ... [Read more...]

Parse pdf files with R (on a Mac)

October 4, 2012 | FelixS

Inspired by this blog post from theBioBucket, I created a script to parse all pdf files in a directory. Due to its reliance on the Terminal, it’s Mac specific, but modifications for other systems shouldn’t be too hard (as a start for Windows, see BioBucket’s script). First, ... [Read more...]

How to check your package with R-devel

September 12, 2012 | FelixS

In response to an update to ggplot2 (now verson 0.9.2) I had to make some minor changes to our package TripleR. The CRAN maintainers also asked to … Please also fix other issues that may be apparent in checks with a current R-devel. Now, how can this be done? Here’s my ... [Read more...]
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