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, I knew that Ruby and Rails are updated regularly and that the setup of the environment might be tricky. And using my Mac not only for web-development, I did not want to have many versions of Ruby, Python, whatnot, in parallel on it. And as I read about Vagrant some weeks ago, I wanted to give it a try.

It took quite some time to set-up the provisioning script properly. I tried using Chef, but it made things more complex and I appreciated the simplicity of a shell script. Continue reading “Vagrant VM for starting a Rails project”

The Valley of Shit

Having only started my PhD studies a few months ago, I am still eager and highly motivated to finish what I have just started. However, first doubts on the topic and the quality of my work already came (and went again, luckily), so I could relate to this post on the Valley of Shit:

The Valley of Shit is that period of your PhD, however brief, when you lose perspective and therefore confidence and belief in yourself. There are a few signs you are entering into the Valley of Shit. You can start to think your whole project is misconceived or that you do not have the ability to do it justice. Or you might seriously question if what you have done is good enough and start feeling like everything you have discovered is obvious, boring and unimportant. As you walk deeper into the Valley of Shit it becomes more and more difficult to work and you start seriously entertaining thoughts of quitting.

A great post, that I enjoyed reading. I will bookmark it to read it again whenever I find myself in such Valley of Shit.

ASA statement on p-Values: Improving valid statistical reasoning

A lot of debate (and part of my thesis) revolve around replicability and the proper use of inferential methods. The American Statistical Association has now published a statement on the use and the interpretation of p-Values (freely available, yay). It includes six principles and how to handle p-Values. None of them are new in a theoretical sense. It is more a symbolic act to remind scientists to properly use and interpret p-values.

Continue reading “ASA statement on p-Values: Improving valid statistical reasoning”

Scientific Hoaxes and Bad Academic Writing

A new case of scientific hoax, that happened six years ago, is currently circulating:

Six years ago I submitted a paper for a panel, “On the Absence of Absences” that was to be part of an academic conference later that year—in August 2010. Then, and now, I had no idea what the phrase “absence of absences” meant. The description provided by the panel organizers, printed below, did not help. The summary, or abstract of the proposed paper—was pure gibberish, as you can see below. I tried, as best I could within the limits of my own vocabulary, to write something that had many big words but which made no sense whatsoever. I not only wanted to see if I could fool the panel organizers and get my paper accepted, I also wanted to pull the curtain on the absurd pretentions of some segments of academic life. To my astonishment, the two panel organizers—both American sociologists—accepted my proposal and invited me to join them at the annual international conference of the Society for Social Studies of Science to be held that year in Tokyo.

Continue reading “Scientific Hoaxes and Bad Academic Writing”

Mixing up Standard Errors and Standard Deviations

Over at the Non Significance blog, the author describes the case of a paper that has some strange descriptive statistics:

What surprised me were the tiny standard deviations for some of the Variable 1 and 2, especially in combination with the range given.

In the blog post, the author outlines his approach to make sense from the descriptive values. It seems to be likely that the reported Standard Deviations (SD) are actually Standard Errors of the Mean (SEM). I’d like to add to this blog post one argument based on calculus and one argument based on simple simulations to show that SEM’s are indeed much more likely than SD’s.1 Continue reading “Mixing up Standard Errors and Standard Deviations”

Birth Rates and Life Expectancy

Bad enough, that we have to read und hear current failures of thought by right wing populists (article in German only) and many relativizations (comments in German only). It seems like 70 years of History class did not help to stop utter racism in public debate.

What, however, sparked my interest was the question what correlations with birth rates there are. My intuitive expectation was, that higher life expectancy is linked to lower birth rates, what might also be explained from an evolutionary perspective.
Now, I’m neither an anthropologist nor do I know the current state of research and I can only use openly available statistics. Luckily, the World Bank has a large database with various indicators for all countries and regions of the world.

Continue reading “Birth Rates and Life Expectancy”

Sorting Data independently before Regression

This thread on StackExchange is circling around my Twitter timeline today and I couldn’t resist sharing it here:

Suppose we have data set (X_i, Y_i) with n points. We want to perform a linear regression, but first we sort the X_i values and the Y_i values independently of each other, forming data set(X_i, Y_j). Is there any meaningful interpretation of the regression on the new data set? Does this have a name?

I don’t want to blame the author of the question. It just offers plain ignorance of basic statistical concepts. On first sight this might be a beginner’s misunderstanding, but this totally kills it:

But my manager says he gets “better regressions most of the time” when he does this […]. I have a feeling he is deceiving himself.

This isn’t incompetence anymore – this is deliberate torture of statistics.