The Success of Stack Exchange: Crowdsourcing + Reputation Systems

May 3, 2012

You’ve heard me say it before… Crowdsourced websites like StackOverflow and Wikipedia are changing the world.  Everyone is familiar with Wikipedia, but most people still haven’t heard about the StackExchange brand question and answer sites.  If you look into their success, I think you’ll begin to see how the combination of crowdsourcing and online reputation systems is going to revolutionize academic publishing and peer-review.

Do you know what’s happened to computer programming since the founding of StackOverflow, the first StackExchange question and answer site?  It has become a key part of every programmer’s continuing education, and for many it is such an essential tool that they can’t imagine working a single day without it.

StackOverflow began in 2008, and since then more than 1 million people have created accounts, more than 3 million questions have been asked, and more than 6 million answers provided (see Wikipedia entry).  Capitalizing on that success, StackExchange, the company which started StackOverflow, has begun a rapid expansion into other fields where people have questions.  Since most of my readers do more statistics than programming, you might especially appreciate the Stack Exchange for statistics (aka CrossValidated).  You can start exploring at my profile on the site or check out this interesting discussion of machine learning and statistics.

How do the Stack Exchange sites work?

The four most common forms of participation are question asking, question answering, commenting, and voting/scoring.  Experts are motivated to answer questions because they enjoy helping, and because good answers increase their prominently advertised reputation score.  Indeed, each question, answer, and comment someone makes be voted up or down by anyone with a certain minimum reputation score.  Questions/answers/comments each have a score next to them, corresponding to their net-positive votes.  Users have an overall reputation score.  Answers earn their author 10 points per up-vote, questions earn 5, and comments earn 2.  As users gain reputation, they earn administrative privileges, and more importantly, respect in the community.  Administrative privileges include the ability to edit, tag, or even delete other people’s responses.  These and other administrative contributions also earn reputation, but most reputation is earned through questions and answers.  Users also earn badges, which focuses attention on the different types of contributions.
Crowdsourcing is based on the idea that knowledge is diffuse, but web technology makes it much easier to harvest distributed knowledge.  A voting and reputation system isn’t necessary for all forms of crowdsourcing, but as the web matures, we’re seeing voting and reputation systems being applied in more and more places with amazing results.
To name a handful the top of my head:
  • A couple of my friends are involved in a startup called ScholasticaHQ which is facilitating peer-review for academic journals, and also offers social networking and question and answer features.
  • The stats.stackexchange.com has an open-source competitor in http://metaoptimize.com/qa/ which works quite similarly.  Their open-source software can and is being applied to other topics.
  • http://www.reddit.com is a popular news story sharing and discussion site where users vote on stories and comments.
  • http://www.quora.com/ is another general-purpose question and answer site.

It isn’t quite as explicit, but internet giants like google and facebook are also based on the idea of rating and reputation.

A growing number of academics blog, and people have been discussing how people could get academic credit for blogging.  People like John Ioannidis are calling attention to how difficult it is to interpret the a scientific literature because of publication bias and other problems.  Of course thoughtful individuals have other concerns about academic publishing.  Many of these concerns will be addressed soon, with the rise of crowdsourcing and online reputation systems.

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Quantum Psychology?

February 10, 2010

Let me be frank; I think “The conjunction fallacy and interference effects” (ungated version) is a horrible misuse of math and indicates an embarrassing failure of peer review.

The author, Riccardo Franco, introduces a parameter that does doesn’t have any foundation in the phenomena it is trying to explain, nor is it shown to aid in modeling.

Please tell me I’m missing something.

What?  You’ve never heard of the conjunction fallacy? It is yet another cognitive bias studied by Amos Tversky and Daniel Kahneman.  They gave people the following problem (quoting from Wikipedia):

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.
Which is more probable?

  1. Linda is a bank teller.
  2. Linda is a bank teller and is active in the feminist movement.

Read the rest of this entry »


assessing peer review

November 13, 2009

Here’s an interesting paper (may require login) from the Journal of the Royal Society of Medicine. From the abstract:

Design 607 peer reviewers at the BMJ were randomized to two intervention groups receiving different types of training (face-to-face training or a self-taught package) and a control group. Each reviewer was sent the same three test papers over the study period, each of which had nine major and five minor methodological errors inserted.
Results The number of major errors detected varied over the three papers.The interventions had small effects. At baseline (Paper 1) reviewers found an average of 2.58 of the nine major errors, with no notable difference between the groups.The mean number of errors reported was similar for the second and third papers, 2.71 and 3.0, respectively. Biased randomization was the error detected most frequently in all three papers, with over 60% of reviewers rejecting the papers identifying this error. Reviewers who did not reject the papers found fewer errors and the proportion finding biased randomization was less than 40% for each paper.

The thing is, i am having a relatively difficult time convincing myself that the comparison they made is the interesting one. When reviewing a paper, are we really ever looking for all of the errors in the piece or just enough to sufficiently determine whether to accept/reject the article? So, how interesting is the difference in the “number of errors found” among those who rejected the paper? To me, not very. This doesn’t undermine their conclusion:

Conclusions Editors should not assume that reviewers will detect most major errors, particularly those concerned with the context of study. Short training packages have only a slight impact on improving error detection.

My question is do you find the question interesting, or would you have sliced the data a different way?

(HT: Michelle Poulin)