About Martin Van der Linden

I am a PhD Student in Economics at Vanderbilt University. My research interests revolve around Market Design, Mechanism Design and Social Choice Theory.

Compelling news article on the replication crisis


One of my favorite excerpt:

“Beyond a few cases of outright misconduct, these practices are rarely done to deceive. They’re an almost inevitable product of an academic world that rewards scientists, above all else, for publishing papers in high-profile journals—journals that prefer flashy studies that make new discoveries over duller ones that check existing work. People are rewarded for being productive rather than being right, for building ever upward instead of checking the foundations. These incentives allow weak studies to be published. And once enough have amassed, they create a collective perception of strength that can be hard to pierce.”

Soon @ Emory

I am very happy to announce that, as of next academic year, I will be joining the faculty of the Institute for Quantitative Theory and Methods at Emory University as a Visiting Assistant Professor.

I’ve had two very good years with the Department of Economic and Finance at Utah State University. It’s a great, growing department with lots of excellent and welcoming colleagues that I will miss. USU will always remain a special place for me and I certainly hope to be visiting Logan in the future.

Classquestion.com, the free alternative to IClicker

I wanted to make my 100+ students class a little more interactive this Fall. So I looked into live Q&A tools.

The most famous one is IClicker. But I thought it was overpriced and I didn’t not want  my students to have yet another thing to pay for.

Then, I discovered classquestion.com.

Classquestion can be accessed from any browser, both on smartphones and on computers. I’ve tried it in class with my students and it works like a charm so far. There are still a couple of functionalities that could be added (such as the possibility to include a TA for your class, or a full-fletched and seamless Canvas integration), but it really does most of what IClicker does.

What is more: it is completely free and relies on a donation-based business plan.

So I figured I’d make a little donation and save my students the cost of IClicker. It’s hard to evaluate how much money that saved them because IClicker has different pricing schemes and students may use ICliker in different classes. But if students want to use the IClicker app, the cost is around $20 per year (cheaper options involve buying a remote, which to my knowledge do not expire, …. until a new version of the remote comes up and is required by a teacher). So I guess I saved my 100+ students a total or anywhere between $500 and $2000 this semester?


Basic arithmetic in Latex

More and more, I use Latex as scratch paper, sometimes to develop numerical (counter-)examples. I often find it much cleaner and better organized than if I rely on actual pen and paper.

Numerical examples are usually a “back and forth” kind of business, with many moving parts. You have to find the numbers that “make it work here” without “changing things there”.

So finding the right combination of numbers often requires a lot of simple (but error-prone) calculations. In that matter too, Latex can save you time and prevent mistakes.

With pen and paper, you would usually (a) write down your arithmetic (e.g., (1/3)*57 + (1/4)*23 + (5/12)*20), (b) use a calculator or spreadsheet to perform the calculation, and (c) write down the result on your sheet of paper.

There are many ways to make mistakes and loose time in that process. As often, Latex offers a solution.

Have a look at https://tex.stackexchange.com/questions/30081/how-can-i-sum-two-values-and-store-the-result-in-other-variable. Very much like you would if you were using Markdown, Latex — with the help of a particular package — lets you,  (a) write down your arithmetic and (b) simply ask your computer to calculate the result.

The code looks something like this:

\usepackage[nomessages]{fp}% http://ctan.org/pkg/fp

(1/3)*57 + (1/4)*23 + (5/12)*20

$(1/3)*57 + (1/4)*23 + (5/12)*20 = \result$


As illustrated in https://tex.stackexchange.com/questions/30081/how-can-i-sum-two-values-and-store-the-result-in-other-variable, you can easily round decimals to your liking:

\usepackage[nomessages]{fp}% http://ctan.org/pkg/fp


$100/3 = \result$



p-hacking (and other data manipulations) made TED-mainstream?

I am not a big fan of the last part of the talk that is too optimistic about randomized control trials and may make then look like some sort of panacea. RCTs have important limitations, especially when it comes to external validity. If you run enough of them, you are bound to find the kind of patterns Laura Arnold seems to criticizes using the 15 ingredients study (7:20 in the video). What works here now might not work there tomorrow. Eventually, you need structural models and sound theory to understand when a treatment works, and when it does not.

That’s the curse of the TED format. Arnold is somewhat critical of the format, but she has to fit in it. I am sure she and the organizations she advocates for know of the limits of RCTs. But there’s only so much you can say in 18 minutes if you want to conclude on an uplifting note.

Still, the overall message is very much worth spreading. It’s important to popularize notions like p-hacking and file drawer effect that rarely even make it into introductory statistics class. And it’s nice to see TED being a little critical of itself (or rather TEDx being critical of TED).