Flatliners Game 1

Well the flatliners (aren't we clever and funny....) just had our first softball game. I am bigger than one guy on the team we played against. I played catcher which in softball is somewhere around playing right field and sitting out. I did make it to first once since the guy playing first fumbled the ball for a moment.

I am proud to say we made it to the 5th inning before the score reached 18 to 3 and the mercy rule kicked it. Considering the other team had 14 runs in the first inning it actually lasted longer than expected.

Here's something I do think is clever and funny:

The after after life

For this blog post let's assume there is an after life. Then I wonder if people, souls, whatever, in the after life believe in an after after life and feel that they have to live their after life in a certain way to be rewarded in the after after life.

It might seem silly to think there would be an after after life since the after life lasts for eternity so what is this after after life to worry about. I'm thinking something along the lines that the number of seconds spent in the after life equals the number of integers (aleph_0), but the number of seconds in the after after life equals the number of real numbers (aleph_1). So you better be good during the after life because the after after life is infinitely longer.

Now you might argue that if the after life lasts an infinite amount of time how could there be something after it. Logically it doesn't work. Well, first of all, an after life doesn't work logically either (I can just hear someone saying "you can't prove there's nothing after eternity" and someone else groaning in frustration). Remember I'm only asking if people in the after life believe in an after after life, not if an after after life exists. Plus if there was an after life all of the believers would have really shown up the skeptics so people would probably be willing to believe just about anything. Every argument would be ended by "you said the same thing about the after life." Can you imagine hearing that line an infinite number of times?

Of course the logical extension is to ask about an after after after life, although that would require a lot of discussion of Godel and your choice of axioms (although people in the after after life who are into faith would love it because you truly could not prove it either way...). I figure I've got a while before I have to worry about the after after after life, so I'll stop here for now.

Excel

I was quite surprised by the following information so I feel the need to make a public service announcement about the stdev function in excel. I normally try to resist posting about math, but I think that lots of people use the stdev function.

If you ever use the stdev function in excel it may not be doing what you expect.

Typically the formula for the standard deviation of a set of points is
sqrt(sum((x-m)^2)/n)
where x is each point, m is the mean, and n is the number of points. This formula applies when you have all the points from a population. However, if you only have a sampling of points from a population then the correct formula is actually
sqrt(sum((x-m)^2)/(n-1))
I'll explain why below.

In excel the stdev function actually uses the n-1 formula. If you want the formula that divides by n the correct function is stdevp. Clearly picking the correct one only matters if you have a small number of points, since as n gets big the difference between the two becomes small. But if you are looking for the standard deviation of a few points it can make a big difference.

Standard deviation is about the distance of points from the mean. If you have the full population then you know the mean of the population and you know the distance from every point to the mean. So you have n distances that you are using. However, if you are only taking samples from a population then you do not know the mean of the population. So you create a mean from the points you have. But if you have two points then you really only have one distance, and you cut it in half by using the mean of your samples. So in this case you really have n-1 distances (by not having the population mean you have one less degree of freedom).

A quick check: If the entire population is one point then the mean equals that point and you divide by 1 so the standard deviation is zero. If you take one sample point from a larger population then the sample mean equals the one point so the numerator is zero and n-1 = 0 so it's 0/0 which is indeterminate which makes sense since if you only take a single sample you cannot estimate the standard deviation of the population.

I had never heard of the n-1 case before today and pieced together this explanation so don't trust it too much, but do be careful if using stdev with a small number of points.

The tortoise and the hare

I'm sure everyone remembers the tortoise and the hare and the lesson that slow and steady wins the race. I have no problem with the moral, in fact I've been making arguments along similar lines lately, which is what got me thinking about the story. But the fable never struck me quite right. I now realize it is because the moral and the story don't fit together. The moral is don't be an idiot or don't be an arrogant ass or... Slow and steady wins the race doesn't fit, because a hare that was actually determined to win would have gone fast and left the tortoise in the dust, and in fact if there was another rabbit in the race the one that loses in the story might have won since he would have taken it seriously and not bothered with the nap. Maybe the moral is actually to challenge yourself. If the fable was changed to where the rabbit had to take a nap because he was so tired from sprinting then the moral would fit.

That has been bothering me since childhood and I'm glad that we now have technology that allows me to broadcast that frustration to the world.

HP 2&3

I read HP 2&3. It seems like the series gets better as it goes. Similar to the movies I was much more into 3 than 1 or 2.

I have never been that convinced by the arguments that violence on TV causes people to be violent (maybe one of the trained neuroscientists reading this will actually know if that is true or not). But I have noticed that what I watch and read does impact what I eat. When I watch firefly I go in search of fruit - Kaylee just looks so happy when she has strawberries. When I was reading HP 3 I bought chocolate for the first time in months, maybe even a year - for some reason I pictured them eating standard milk chocolate, but I go for 70% or bust. Luckily all that BSG watching hasn't enticed me to start smoking or drink ambrosia (although they usually don't look that happy about either one).

For the firefly fans out there, who don't track xkcd (probably a null set, but anyway):
http://xkcd.com/311/

In case it is not clear from the rest of this post - I spent a lot of time inside reading HP and watching BSG over labor day weekend. Southern California let me down with a 100 degree weekend. Luckily it cooled back down by tonight for my company's softball team's second practice.