Have you considered the opposite?
Yes, and I'm familiar with your IQ-related links in the OP*. But what's the opposite here? Let me make sure my position is clear: I agree that the people who post on LW are noticeably cleverer than the people that post elsewhere on the internet.
The narrow claim that I'm making is that the average self-reported IQ is almost definitely an overestimate of the real average IQ of people who post on LW, and a large change towards the likely true value in an unreliable number should not be cause for alarm. The primary three pieces of evidence I submit are:
On this survey, around a third of people self-reported their IQ, and it's reasonable to expect that there is a systematic bias, such that people with higher perceived IQs are more likely to share them. I haven't checked how many people self-reported on previous surveys, but it's probably similarly low.
When you use modern conversion numbers for average SAT scores, you get a reasonable 97th percentile for the average LWer. Yvain's estimate used a conversion chart from two decades ago; in case you aren't familiar with the history of psychometric testing, that's when the SAT had its right tail chopped off to make the racial gap in scores less obvious.
The correlation between the Raven's test and the self-reported IQ scores is dismal, especially the negative correlation for people without positive LW karma. The Raven's test is not designed to differentiate well between people who are more than 99th percentile (IQ 135), but the mean score of 127 (for users with positive karma) was 96th percentile, so I don't think that's as serious a concern.
* I rechecked the comment you linked to in the OP, and I think it was expanded since I read it first. I agree that more than half of people provided at least one IQ estimate, but I think that they should not be weighted uniformly; for example, using the self-reported IQ to validate the self-reported IQ seems like a bad idea! It might be interesting to see how SAT scores and age compare- we do have a lot of LWers who presumably took the SAT before it was dramatically altered, and with younger LWers we can compare scores out of 1600 to scores out of 2400. It's not clear to me how much more clarity this will give, though, and how much the average IQ of LW survey responders actually matters.
What IQ would you correlate to the SAT numbers, considering?
As for the Raven's numbers, I am not sure where you're getting them from. I don't see a column when searching for "raven" in the 2012 spreadsheet, nor do I see "raven" on the survey result threads.
Various people raised concerns that growth might ruin the culture after reading my "LessWrong could grow a lot" thread. There has been some discussion about whether endless September, a phenomenon that kills online discussion groups, is a significant threat to LessWrong and what can be done. I really care about it, so I volunteered to code a solution myself for free if needed. Luke invited debate on the subject (the debate is here) and will be sent the results of this poll and asked to make a decision. It was suggested by him in an email that I wait a little while and then post my poll (meta threads are apparently annoying to some, so we let people cool off). Here it is, preceded by a Cliff's notes summary of the concerns.
Why this is worth your consideration:
- Yvain and I checked the IQ figures in the survey against other data this time, and the good news is that it's more believable that the average LessWronger is gifted. The bad news is that LessWrong's IQ average has decreased on each survey. It can be argued that it's not decreasing by a lot or we don't have enough data, but if the data is good, LessWrong's average has lost 52% of it's giftedness since March of 2009.
- Eliezer documented the arrival of poseurs (people who superficially copycat cultural behaviors - they are reported to over-run subcultures) which he termed "Undiscriminating Skeptics".
- Efforts to grow LessWrong could trigger an overwhelming deluge of newbies.
- LessWrong registrations have been increasing fast and it's possible that growth could outstrip acculturation capacity. (Chart here)
- The Singularity Summit appears to cause a deluge of new users that may have similar effect to the September deluges of college freshman that endless September is named after. (This chart shows a spike correlated with the 2011 summit where 921 users joined that month, which is roughly equal to the total number of active users LW tends to have in a month if you go by the surveys or Vladmir's wget.)
- A Slashdot effect could result in a tsunami of new users if a publication with lots of readers like the Wall Street Journal (they used LessWrong data in this article) decides to write an article on LessWrong.
- The sequences contain a lot of the culture and are long meaning that "TLDR" may make LessWrong vulnerable to cultural disintegration. (New users may not know how detailed LW culture is or that the sequences contain so much culture. I didn't.)
- Eliezer said in August that the site was "seriously going to hell" due to trolls.
- A lot of people raised concerns.
Two Theories on How Online Cultures Die:
Overwhelming user influx.
There are too many new users to be acculturated by older members, so they form their own, larger new culture and dominate the group.
Trending toward the mean.
A group forms because people who are very different want a place to be different together. The group attracts more people that are closer to mainstream than people who are equally different because there are more mainstream people than different people. The larger group attracts people who are even less different in the original group's way for similar reasons. The original group is slowly overwhelmed by people who will never understand because they are too different.
Poll Link:
Endless September Poll.
Request for Feedback:
In addition to constructive criticism, I'd also like the following:
Your observations of a decline or increase in quality, culture or enjoyment at LessWrong, if any.
Ideas to protect the culture.
Ideas for tracking cultural erosion.