Thanks to everyone who commented and read through my post last night.  The post got a lot more attention than I expected (on hacker news and reddit at least).    Many comments both here and on those threads quite reasonably pointed out problems with the data presented.  I should have been a lot more clear initially about the caveats and issues, and put those at the front of the post instead of the end.

I’d like to try to address some of the concerns raised when possible, and be clear about which problems I don’t see an easy way of fixing:

Confidence intervals

Many commenters have noted that the results are not significant without including confidence measures.  In retrospect I should have calculated confidence intervals from the beginning instead of just the mean values; I had assumed incorrectly that the n=100 cutoff would keep the error low enough to ignore, but that was a mistake.  Below is an updated graph with 95% confidence intervals:

and the numbers:

Language	Mean	Lower	Upper	Samples
Puppet	87,589.29	77,726.24	97,452.33	112
Haskell	89,973.82	82,773.72	97,173.92	191
PHP	94,031.19	90,956.90	97,105.47	978
CoffeeScript	94,890.80	90,025.16	99,756.45	435
VimL	94,967.11	90,735.70	99,198.51	532
Shell	96,930.54	93,771.76	100,089.33	979
Lua	96,930.69	86,169.26	107,692.13	101
Erlang	97,306.55	88,631.11	105,981.98	168
Clojure	97,500.00	91,448.24	103,551.76	269
Python	97,578.87	95,481.64	99,676.10	2314
JavaScript	97,598.75	95,897.67	99,299.83	3443
Emacs Lisp	97,774.65	92,503.64	103,045.65	355
C#	97,823.31	94,116.76	101,529.86	665
Ruby	98,238.74	96,471.81	100,005.68	3242
C++	99,147.93	95,633.62	102,662.23	845
CSS	99,881.40	95,361.99	104,400.82	527
Perl	100,295.45	97,172.79	103,418.12	990
C	100,766.51	98,602.83	102,930.19	2120
Go	101,158.01	94,435.87	107,880.15	231
Scala	101,460.91	94,925.79	107,996.02	243
ColdFusion	101,536.70	93,627.35	109,446.05	109
Objective-C	101,801.60	97,560.43	106,042.77	562
Groovy	102,650.86	94,601.74	110,699.99	116
Java	103,179.39	100,474.36	105,884.42	1402
XSLT	106,199.19	96,887.72	115,510.65	123
ActionScript	108,119.47	99,297.36	116,941.58	113

As it turns out, the commenters who noted that the top and bottom languages were likely because of small samples were correct.  Although the confidence ranges of the top and bottom groups don’t overlap, the difference is not as clear-cut as the means would suggest.

I’m going to try to gather some data from sparser-represented languages to clean this up, and will update here when I have better numbers (this might take a while because of API rate limiting.)

Household Income vs Personal Income

Many commenters noted that these numbers use household income rather than personal income.  This is a limitation of the data sets I’m using rather than voluntary; the Rapleaf API only returns household income.  Rather than give up I decided to use the household measure instead.

This is not ideal, but I don’t think it is a critical flaw; for this difference to skew the results, authors of certain languages would need significantly different marriage patterns or a tendency to marry richer / poorer spouses relative to other languages.  This is not impossible, but I think the results are still useful with this caveat in mind.

If anyone can suggest a data set with personal incomes I can use instead, I’ll gladly use those.  Otherwise I’ll be more clear that the incomes are household rather than personal.

Correcting for Confounding Variables

The original numbers did not attempt to adjust for any other variables, some of the more obvious being age and location.  It’s been suggested that I look into using partial dependence plots to separate out other variables.  I’ll be taking a look at that over the next few days.

Missing Languages

Unfortunately there’s not a lot I can do about many missing languages; many are not recognized by GitHub (SQL, among others).  As I gather more data, I’ll include the languages which were omitted here because of sample size.

Thanks again to everyone who read and commented.  I’m going to process the lessons here and be more careful when posting numbers in the future (I’d still like to give similar breakdowns for gender and age soon.)

I’ve always been casually interested in the field of Natural Langauge Processing (NLP), a  field of computer science interested in extracting information from natural human language. I have no training or education whatsoever in the field so I’m not in a position to contribute much to the field, but I am definitely interested in seeing where the state of the art is, and in particular how powerful open-source NLP libraries have gotten (Google and Microsoft certainly have more powerful closed-source systems, but that doesn’t really help me.)

A few years ago I started playing with Apache’s OpenNLP project.  I’m a big fan of the Apache foundation and their libraries, but I found myself very frustrated by OpenNLP’s lack of documentation and the hacky-feeling interfaces the library exposed.  However recently I took another look at the available NLP libraries and came across Stanford’s CoreNLP project.   CoreNLP, as it turns out, is an awesome project, and it took almost zero effort to get their example demo working.

As a total NLP beginnner, the sentence parsing functionality was the most immediately approachable example.  Sentence parsing takes a natural-English sentence:

“I am parsing an example sentence.”

and breaks it down into component tokens and their relations:

(ROOT (S (NP (PRP I)) (VP (VBP am) (VP (VBG parsing) (NP (DT an) (NN example) (NN sentence)))) (. .)))

where each token type corresponds to a particular word type–“NP”  means “Noun Phrase”, VBG means “Verb, gerund or present participle”, and so forth (I’ve been referencing this as a complete token list.)

I’ve also been looking into JavaScript graph visualization libraries recently (I’ve struggled to find a JS library remotely as powerful and pretty as graphviz), and wanted to test out the dagre library, which re-implements a simplified dot algorithm in javascipt and can render the results to d3 (the current coolest-kid-on-the-block JS graph library).  So I put the two together and put together a simple visualization which uses dagre to show CoreNLP’s sentence parse tree.  It’s pretty simple, but you can play with it here.

When I have time to work with the two libraries a bit more I’ll hopefully update with something more interesting.

For the past couple weeks I’ve been working on a project to visualize and compare the demographics of popular GitHub organizations by combining data from the the RapLeaf and GitHub APIs.   By pulling emails from Git commit data and querying the Rapleaf API for demographic data, I was able to put together an aggregate picture of the age + gender + income of people who have contributed to a GitHub organization (shown below for the Rails organization)

• See more details on how the data was gathered here,
• See organization ranked by age / gender / income here
• Browse all available organizations here.

I’ll be following up soon with some thoughts on the results.  For now, I’ll just point out that Linux kernel developers make serious bank.