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   Revision #6 - 6/11/2009 9:32 PM     

Podcast 057


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Spolsky: First of all, yes we got a lot of positive feedback from the Jason Calacanis podcast which actually sort of surprised me.

Atwood: That's good because you were very worried about that.

Spolsky: I was worried that our developers would be like, oh ick, he's one of those business guys.

Atwood: Yeah, Jason's pretty cool though, I vetted, I listened to a couple of podcasts he was on and gave him my thumbs up so.

Spolsky: Uh hu.

Atwood: My gut feeling was that it would be OK.

Spolsky: He's like one of the smartest people I ever talked to.

Atwood: Yeah, he's smart but you know I still don't agree that Mahalo is doing the right thing.

Spolsky: No, but that doesn't, you know, yeah.

Atwood: <laughs>

Spolsky: He's just a smart guy. I also, there's a couple of things about Mahalo. One is it sort of disturbs me their traffic seems to be relatively flat like, if it's really going to work it should be taking off. But you know maybe they'll change something and then it will go up. And also I totally, I still disagree with Jason and really don't think that they should ever, um, try to pay people for sex, so to speak.



Spolsky: Tell the listerners what Fizz-Buzz is.

Atwood: Well Fizz-Buzz is a simple test to count to 15, and I think, print numbers at intervals of 3 and 5, I believe ...

Spolsky: Right, so basically you print Fizz, if it's not divisible by 3 or 5, and you print Buzz if it's divisible by 3 or 5.  Yeh, this problem is even easier than that.

Atwood: Really!

Spolsky: Yeh! 'Cause Fizz-Buzz has a loop, an if statement and modulo, right?

Atwood: Yep.

Spolsky: And print.  This doesn't have print, this doesn't have a loop.

Atwood: Wow, this is even simpler! Wow!

Spolsky: Yeh!  I don't want to tell ... fine I'll tell people.  No, I'll give you an equivalent problem which is not the same problem.

Atwood: Giving away the secret!  I don't think the people that you give the secret away to are going to matter for this one.

Spolsky: It's sort of something like ... is John older than Mary?  <Laughter>  It's a little harder than that!  Uhm, anyway, uh, what happens when I ask this question is that everybody gets it, but some people take a long time to think it out, and they're carefully thinking it through, and they really are struggling, and some people just write really fast and they're done.  And then we can move on to more advanced things.  And, it suddenly occurred to me, that there was a very high correlation between the people that I hired, and the people that could solve this problem as fast as they could write.


Spolsky: I told this story to Gary Cornell, my publisher at Apress who used to be a math professor at University of Connecticut. Before he became the best-selling author of "Core Java" and started Apress he was a math professor. He said this reminds me of something Serge Lang said to him. Serge Lang is a math professor at Yale who is very interested in math education. Serge Lang at the beginning of freshman calculus at Yale, gave people for no credit, took out, told all the students to take out a piece of paper, and he put a fairly simple equation up on the board and said reduce this to its simplest terms. So this is basically 9th grade algebra. Then after like 30 seconds he said "stop!" and took all their pieces of paper.

Some students were able to reduce this algebra equation to its simplest form as fast as they could write, and some of them really had to think about it and really had to work on it. I would have been in that category, the second category. And he said that the people that could do it quickly was an almost perfect predictor of who would get an A in the course. In other words that was as good a predictor of math ability, as an entire semester in Calculus with problem sets every week and probably two mid-terms and a final. Was just like how fast can you solve a simple algebra problem that has nothing to do with calculus, it is using calculus but it is like a real simple algebra problem. The whole story is in my book "Smart and Gets Things Done".

Actually let me see if I can find what the problem... I can't remember the exact equation. Cornell, page 108, "Smart and Gets Things Done". Oh yeah, you basically had to simplify... our math majors will recognize this ....

1/(x + h) - 1/x
which is something you do basically to figure out derivatives, and you just have to simplify that to its ....

[67:51 ends]

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Last Modified: 8/25/2009 11:29 AM

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