I considered putting down my IQ, but decided that would be a bit tacky so I just listed some of the areas of technology that interest me or that I feel I'm good in.
IQ and SAT stats do not strongly correlate with performance anyway.
SAT scores correlate highly with academic performance. This should come as no surprise, since their whole purpose was to democratize college admissions by allowing those students who would do best at college to be accepted, regardless of their religion or social connections.
The fact that SAT scores correlate poorly with workplace success is a red herring -- SAT scores were never supposed to predict workplace success.
SAT scores are actually pretty decently correlated with freshman year grades. Colleges wouldn't use it if it weren't predictive, and so the College Board has put a lot of work into ensuring the test means something. Then again, freshman year grades don't really mean much in the grand scheme of life, but they do mean something, definitely.
I put down my SATs - the 7th grade CTY ones, not the official high school ones. I figure that many applicants have perfect or near-perfect SATs, so I wouldn't stand out so much on that basis. I debated taking them off as tacky, but I figure that I've already posted a lot about my experiences on this board, while the test scores and such is new information.
Ultimately, I think experience matters more, but there's a whole other section on the app for "What have you built?" and another one for "What tools will you use?"
IQ and SAT might provide benchmarks for intelligence, but they have no correlation with the desire and ability to complete a large task. Everyone knows that smart kid in high school/college who sat around playing WOW and drinking Mt Dew all day. Y Combinator does not want him.
In addition, sometimes the not-as-smart kid who has a good idea and a lot of motivation can accomplish something great.
If you did not spend months working on something, possibly crying at times with frustration and jumping around euphorically when you hit a new milestone, you have not done something with a high level of ability.
Any time someone mentions "ability", you should ask "... to do what?"
If you're looking for ability to find new algorithms and prove their correctness, I probably win. If you're looking for ability to build a robust application (which is a key point to me -- I'm working on online backups, and the central point of backups is that they do NOT lose data, even if hardware failure occurs) I might win. If you're looking for ability to create an engaging Web 2.0 site, I definitely lose.
I'd assume that what YC means by "ability" is "ability to create whatever you've said on the application form that you intend to create" -- which in my case was an efficient, robust, and secure online backup system, but for most applications would be an engaging Web 2.0 site.
EDIT: Incidentally, it didn't even occur to me to mention the Putnam on the YC application form. For the "high level of ability" question I pointed towards my BSDCan'05 paper concerning stealing RSA keys on Intel CPUs with HyperThreading via an architectural side channel.
This question is all about showing that you have achieved a level of excellence in a particular field. This could be academically (having won awards) or entrepreneurially (having set up stuff or had a large impact on people) or creatively (being incredibly awesome at jazz piano).
Think of a situation where you show above average ability relatove to someone. The truth is high achievers will continue to do so irespective of field - so if you want to be the best in the startup world try and extrapolate back to comsthing you have achieved.
Perhaps you could describe accomplishments that require a high level of ability. Perhaps you could include your academic papers, patents, contributions to open source projects, extracurricular engineering projects, or business adventures.
If you can't talk about something like that, I don't think you can demonstrate a high level of ability. Otherwise, do something great or work for someone who can.
I think this is a useful metric for evaluating a startup team, but I do think the metric is subjective!
I am sure a lot of us (not so fortunate ones) realize our best abilities while working on something we really love.
So the best bet would be to describe your abilities relative to the problem you are trying to solve. How are your abilities helping your startup make significant forward progress?
Maybe people should see how much others improved at their extra-curricular activities since they took them. You are not forced to do those (as you are forced to study for some exams or go to work), you do them because you have fun with them. Then, what you would really be measuring is how determined the person in question is to be better. That's an ability too.
Using IQ scores to measure people is extremely efficient. A 15 minute test can give you a good, rough idea of what sort of work a person is capable of. Someone who gets an 85 on an IQ test isn't going to MIT (no matter the effort), whereas a person with a 145 probably could (with effort).
This is mainly useful in situations optimized for efficiency--think mass inductions, as into the army or college, where individually judging people isn't possible. The army can't send everyone to officer school, and Harvard can't give everyone a one-semester tryout.
This isn't the situation faced by investors, who can devote more time to distinquishing people.
IQ and SAT stats do not strongly correlate with performance anyway.