<p>Yeah... the folks at the SURF office will have a firm number. By the way, the Committee on Undergraduate Research for this year's Student Faculty Conference did some surveying, and while I don't remember the fraction, there was a substantial number of people who wanted a SURF and said they couldn't find one. But obviously this would be skewed by the issue of who decides to respond to the survey.</p>
<p>However, to echo cghen, if you do the following things, the probability of not succeeding becomes much lower.</p>
<p>(1) start asking in December-January;
(2) find tenured (or at least well funded) people who are supervising/have supervised a fair amount of research; you can tell someone is tenured if their position is "professor" (and sometimes "associate professor" -- people will usually note on their CV if they are untenured associate professors)
(3) generally act professional and make a strong, proactive case about why you would be a good research colleague;
(4) ask several different people fitting the description in (2) if at first you don't succeed</p>
<p>On (1), Techers are famous procrastinators. Usually this is okay, because it's only you who has to stay up the night before things are due. But in this case, you need a professor to also think through things and support the application. Few professors will be excited about the mad rush to submit documents days before the official SURF deadline. It is okay if you don't want to do research, but if you do, then do yourself the favor of starting early.</p>
<p>On (2), I made something of a misstep after my frosh year in applying to work with a postdoc in math, who wasn't well funded and wasn't part of a bigger research group. In the end, the SURF went fine, but whether it would get funded was up in the air for a while. If you work with tenured faculty, things are typically much smoother. (See this [url="<a href="http://www.et.byu.edu/%7Etom/jokes/Rabbit_Thesis.html%22%5Djoke%5B/url">http://www.et.byu.edu/~tom/jokes/Rabbit_Thesis.html"]joke[/url</a>] on this subject.)</p>
<p>(3) You are not in elementary school, so it is not okay to introduce yourself to a prof by saying "I was thinking if maybe you had some research for me to do?" Before you approach a professor, you should have read at least some work in the area or you should be obviously valuable for some other reason (like your knowledge of methods the professor is interested in using). In any case, you should have something intelligent to say (but don't pretend to know more than you do). You should also put together a short resume or CV detailing your qualifications and make it available to the professor. Even if the professor has taught you, chances are he has very little idea about what you've done. There's no need to overdo it -- you're not applying to college -- but a short and honest summary of your main accomplishments and courses related to your research aspirations will make you look much more serious and worthy of attention.</p>
<p>On (4), someone I know from MIT wanted to do a SURF so she emailed about 5 people, all big shots, and most ignored the message or briefly said they had nothing. The person kept trying and got a SURF in the lab of a very famous professor doing very cutting edge work, did well, and got awesome recommendations. The moral: even people who end up succeeding greatly get viciously rejected repeatedly before the success. Asking for a SURF may only be the first or second time you hear "no" in seeking to do something academic, and it will be unexpected and a little traumatic. But the key to being a successful academic (or most anything really) is to develop a really thick skin. Which is easier said than done. However, see this [url="<a href="http://www.geocities.com/researchtriangle/campus/6791/eletter2.htm%22%5Dletter%5B/url">http://www.geocities.com/researchtriangle/campus/6791/eletter2.htm"]letter[/url</a>].</p>