Cross Acting

I don't get in trouble often, but I consider myself something of a rebel. I don't like organizations in the general much - I prefer groups that are more self organized and sustained. Sometimes I do weird things for amusement, like pretending I don't know a secret to see whether the secret holder would divulge it.

This time, I posted a Criagslist ad... in Women Seeking Men.

The primary question I wanted answered was whether men on the internet are really crazy. Some of my female friends have posted ads for fun, and later compared their replies. What they found was that some emails were exact copies of each other - some people just write the same response to everything, looking for a shag. That story had a twist ending for my friend, but that's not my story to tell.

A word on the post: I didn't write the ad myself - I would never have passed as a female writer. I won't copy the post here, but it was itself copied from the blog of a friend. We haven't talked since I graduated from Northwester, and even before then I don't think she knew I read her writing. She is an objectivist before I read The Fountainhead, and the post expresses a related sentiment: her wish for someone who doesn't want only to please her, but someone who can contribute something of themselves to her. In the words of Ayn Rand, a prime mover, not a second hander. Regardless, I never told her I used her writing (if you're reading this, you should email me), so I don't feel right posting her work even with attribution.

First, some statistics. I got 50 replies in total, the first within the hour, the last almost a month later. About 60% replied within 5 days. 12 of the 50 replies had photos attached, and a few more had links to either MySpace pages or some other picture hosting site. A small minority didn't bother to write proper English for the task, and a few more asked questions which made me think they didn't read the post at all. Although it wasn't unexpected, there were several older men who replied. For an ad declaring the poster to be 22, I got a reply from someone 17 years older. It reminds me of what OKTrends found. Of the 50 replies, two were duplicates; the senders sent the same email twice.

My most common reaction (subject to availability bias) is: who do you think you are? Granted, the post is a little self indulgent, but they are still the suitors. What I had posted talks about an intellectual pursuits... and a fair number talk about sex, and how they "know what a women [sic] wants in the sex department" and that "[I] want to be seduced". At the bottom of the pile is a reply that promised to "open that box of hidden desire and fantasy". I want to puke.

On the other hand, I suspect some responders are delusional. One ranted on about hidden treasure. One had a "real" picture of himself tensing up. A few wrote poems.

As for the good... there aren't the many. The ones I like best (again subject to bias, this time of a different kind) were simpler. They mention how old they are, what they do and like doing (somewhat passionately), and invite me to reply. A picture, if one is included, is a simple face shot. Three people mentioned books/authors, one of them being Ayn Rand. Only a single person mentioned something interesting - by quoting an article on the large hadron collider.

Hypothesis: most men who reply to Craigslist personals are douchebags.

Result: Confirmed.

Maybe next time I'll reply to a men seeking women ad (the doucheist one... is that a word?), and see what I get.

Smashing Cars

I'm kinda unhappy with the latest MythBusters episode, the one about two cars smashing into each other at 50 mph is equivalent to one car smashing into a wall at 50 mph.

The way they tested the myth on a small scale was by swinging two pendulums into each other, with each pendulum containing a lump of clay and an additional weight in the back. The second weight would squash the clay, and from the deformation the impact of the smash can be visualized. It's a pretty clever rig.

My problem, however, is not with the rig; it's with the interpretation of the myth. There are two ways in which the two crashes can be "equivalent": from the perspective of the car, which is what the MythBusters tested, and from the perspective of something in the middle. Since the original myth is about a compact car being squished between two semis, it would seem that this myth should be about the latter interpretation. And in that case, I believe the crashes are, in fact, equivalent.

As an educational show, I think MythBusters should have at least covered this other scenario, and shown how the "myth" is more of an interpretation issue.

Pascal's Wager, Part 2

I have written about Pascal's Wager before, but I never finished that post. A few days ago I came across a video, which finally closed the case on that argument for me.

The inspiration is this, which I found on Reddit. Most of the video is junk and doesn't hold up to my standards of reason. Something at the end caught my attention though, and I came up with the following argument.

Recall that the problem with Pascal's wager is that, unlike most arguments about God, it's a completely rational. It frames the problem in turns of expected utilities, which is the standard practice in decision theory. The following payoff matrix summarizes the wager:

	God Exists	God Doesn't Exist
Believe in God	+Infinity	0
Don't Believe in God	-Infinity	0

Richard Dawkin's argument, that believing in God has a cost while living, doesn't hold up, as any cost incurred while alive is only finite, and does not offset the infinite payoff of being in heaven.

Pascal's wager is that simple. The video over-complicates and sets up several straw men (eg. Pascal not knowing what God is but then contradicting himself) and ad hominem attacks (eg. Pascal's bias towards Christianity). While the claim that Pascal ignores other gods is true, his wager still works - as long as gods reward belief, the expected utility is still to believe in god(s). The existence of non-god systems (frog's dream, video game, etc), doesn't matter, as they don't offer any utility. The gem of the video is in a 3 second frame: for every unknowable idea that rewards a particular behavior, another unknowable idea will punish that very same behavior.

Here's my new argument. Pascal's wager depends on supposing a Christian god, with the payoff matrix above. Since, however, the existence of the Christian god is unknown, it is equally valid to posit a different god (let's call Him AntiPascal), with different payoffs. In particular, let's imagine a god that will send people to heaven only if they don't believe in any god, and will send people to hell if they do. What does the payoff matrix look like?

	God Exists	God Doesn't Exist
Believe in God(s)	-Infinity	0
Don't Believe in God(s)	+Infinity	0

That's right - everything looks almost exactly the same, except the signs on those infinities switched. By this payoff matrix, people should not believe in gods at all.

So which payoff matrix is right? We don't know. To properly calculate the expected utility of believing in god(s), we need to know the probability of each payoff matrix itself - that is, the probability that the Christian god is real (and has the payoff matrix specified), and the probability that the AntiPascal god exists. Both of these probabilities, it turns out, is unknowable - and therefore the expected utility of believing or not believe in god cannot be compared.

Given the odds, Pascal's wager is not one you want to bet on - there's simply no telling whether you win or lose. While this is no argument against the belief in god, it is no longer the purely rational argument for it either.

The funny thing is, although this argument is new to me, the reasoning behind it is not. As Richard Dawkins himself has said several times, most theists are in fact atheists to all other religions. Real atheists just go one further.

Updates

I clearly haven't written here for a while. I have a post halfway written about an adventure on Craigslist (no, it's not from the m2m personals...), which I will finish eventually. For now, here's part of an email I sent to my family.

I just got done with the semester over the weekend. If you'll remember, I'm taking two classes:

• Advanced AI. Like I said last time, this course is oriented towards getting students to read current research and to think critically about it. I think the course did a good job of that - we had to read a large number of papers, all over the map in terms of area. It's interesting too to see how different students react to ideas differently, as well as what areas of AI they are interested in. The final project for the course is to reimplement a study, and see whether their claims hold up. In retrospect, I should have chosen a different paper. Mine was on a relatively simple method of understanding how the world around you changes due to your actions. Although it was an interesting paper, the algorithms and methods were not very well specified, which makes it hard to test. It was also short with very few references, so there's no extra material I could refer to either. I finished it, but I would have enjoyed it more if the paper was more substantial.
• Programming Languages turned out to be more fun than I thought. The basic premise of the course is how to prevent programmers from doing stupid things, and how the computer can automatically detect these errors and notify the coder. We also read a lot of papers here, although a lot of them were older papers. The areas were also more biased towards people without much background, so although we looked at four different methods, we only studied one or two in depth. The final project here was up to us, and I decided to (again) reimplement a paper, this time checking for errors in their presentation. I discovered a few of them, as well as a general problem with the approach it was taking. Because this work is actually someone's thesis back in 2006, everything was documented properly, and I have very little trouble following their work. All this means that I should make my code public when I publish a paper.
  

It was because both of these projects were due last week that I didn't have time to write this email. I was awake both Monday night and Thursday night writing reports, and so had very little sleep. It was fun though; I felt invigorated by how much work I was doing. There's a quote from Ayn Rand's The Fountainhead (Dominique, for those curious), when a character says, "This is how I want to keep going - if there's a reason for it." That was how I felt on morning after staying up - that having a reason to drive myself that hard is the best feeling.

I'm also done with my teaching duties for now. The final exam for that class was on Friday, so we graded everything by Saturday evening. My discussion sections and the class in general is smaller this semester than the last. I got to know the students a little better, but not in pro[portion to the decrease in size. I did realize something though - that I should spend the first few session actively encouraging the students to talk to each other. It's really annoying when you ask a question and no one wants to answer it. So the discussions were not as lively, there were less jokes, and overall it was a little less enjoyable.

Oh, I got an award for being a good TA last semester, which is nice. It also came with an extra check, which is also nice.

On the research front... I'm really digging in now. For a short while back in February I was really uncertain how everything would turn out. That period of doubt clarified my feelings a little - I'm sure now that teaching would have a part in my future, more so than research. On the other hand, very soon after that, I found a topic that I'm pretty interested in, so much that I spent all of this morning reading. We'll see how it turns out. I got put on the spot today to give a 10 minute presentation at a workshop in three weeks time, which means I really have to get my thoughts together and present a coherent picture of what's going on in the field, and what I want to do.

Blogspot Spellcheck

Those of you who read my previous post on hangboards before this might have noticed the strange yellow highlighting. It's fixed now, but it turns out that the spellcheck in the Blogger compose box actually modifies the contents, by inserting span tags like these:

<span class="goog-spellcheck-word" style="background: none repeat scroll 0% 0% yellow;">errorr</span>

And so, if you click spellcheck, then publish it without clicking again, those highlights will be published along with the post. The resulting post will look something like this post.

Hangboard

My roommate and I bought a hangboard (aka a fingerboard) (the Metolius Project ) from our local climbing gym (Planet Rock) about three weeks ago. We're both engineers, and so we decided to design and build a frame to hang the board from. Here's the result:

You can see that the board is simply supported by two A-frames, kept the correct distance apart by two cross members. They're simply built from 2x4's (which I learned actually have a 1.5x3.5" cross section). We had a fun time loading those on a shopping cart to transport them from the hardware store to the apartment. The wider board is a 2x8 (1.5x9.25" cross section). The vertical member of the board is 6 feet long, which puts the hangboard at an excellent height. The base of that triangle is about 42" long, and extends another 30" out for balance. The two A-frames are 42" apart from each other, measured from the inside. The extra space is so we can mount holds on either side, to practice on other holds (for example, vertical pinches).

The construction of the thing took maybe 12 hours in total, spread over three days of spare time (I think). The most annoying part was cutting the angles in the hypotenuse. The angles were cut by hand, which made their tolerance rather loose. We had to sand down the edge quite a bit. The holes shown below were done without any guide to make sure they're perpendicular, but it all worked out in the end.

This is the part of the rig I'm most proud of. The idea is to let the hangboard rotate, so we can practice steeper crimps. The original idea is to move the entire A-frame, locking it in with notches on the base. That would have been a construction nightmare, however, so we came up with this system where just the board rotates. Those holes are 6.25" from the pivot, and there's seven of them going a full 90 degrees.

This is the side of the pivoting mechanism. The center board is held in place by 4 bolts, and the side board is held to the frame by 6 screws each. This view also shows the extra board in the back, which stops the A-frames collapsing sideways. Mounting this board high up keeps it out of the way as we do pull ups, but there's another practical reason. Since the center board is only held by bolts, we can easily take it out and replace it with something else. In particular, if we decide to make a campus board later on, it can use the same holes for tilt, and can extend beyond the A-frame.

We still have a little work to do on it, the most important of which is adding diagonal beams between the frames to stabilize it further. There are also other things like sanding down the corners, clipping some screws on the back of the board, getting a pad underneath, and applying a layer of varnish. The frame right now is fully functional though, and it holds our weight quite well. Although I haven't looked at how other people mount their hangboards (usually just above a doorway, probably), I feel that this is probably the most flexible design you'll find. The flexibility with the angles and the modular design means it can function as a very general purpose climbing trainer.

We intend to have blueprints of the entire thing online eventually, when we're bored enough to play around in a CAD program. If you want to build one in the mean time, feel free to leave a comment and we'll help you out as best we can.

OKCupid is Wrong

I started reading OKCupid's blog about a month ago, when their post hit the front page of Reddit. I don't use the site, but their combination of romance and statistics was intriguing. A new post just came out, and I was procrastinating hard enough to think a little about it. In their post, they argued that men between 22 and 30 should be looking at women 30 and older. They first provided data about what their users say they want, then provided reasons why women of that age are better matches.

There is, however, a flaw in their argument. Their basic error is this: women 30 and older don't want to date men between 22 and 30.

I took a closer look at their graphs, and extracted out the numbers. This is the graph I got:

If this looks slightly different from the graphs on OKCupid's post, that's because it is. Here, I flipped the female match preferences graph along the y=x axis. Therefore, if you're female, you start on the y-axis, and read across to get the average match preference.

Now, on to why OKCupid is wrong. If you look at their "zone of greatness", they marked out this area:

You see the problem: the average person in this area don't want to date others in this area. The blog post was written for men, so their bound might be ignored. The bound for women, however, shouldn't be. And this graph shows that, even if men were willing to date women in that age range, chances are the women won't reciprocate.

In other words, even with the other reasons that women above 30 are great fun, it turns out that they are simply not interested in men between 22 and 30.

What, then, should men (and women) be looking for? Look at the graph below:

Overlooking my horrible circling skills, these are the areas where there is a mismatch between men's preferences and women's preferences. Whereever women's preferences are taller than the men's (or men's preferences wider than the women's), there is an opportunity. Because men accept women of such a wide age ranger, any women who is willing to date someone slightly outside the average range (shown in pink) has an advantage. Comparatively, there are much fewer places where women are interested and men are not (shown in green).

Based on this graph, you can see what age you will have the least competition, but still are still relatively desirable.

One last thing: xkcd should be updated to reflect this data.

Disclaimer: Obviously, I am not affiliated with OKCupid. If any OKCupid staff reads this, and finds my graphs objectionable, please let me know.