cat /proc/claus

This year I gave lectures to three different classes about introductory statistics. One of my favorite classes was Correlation and Linear Regression, because It allowed me to talk to students about more practical applications of the usually very mystical concepts of statistics.

In all three lectures I talked about the “correlation vs causation” dillema, and in all the exams I included the following question: “A group of scientists find out that the rate of use of product X has a strong correlation with the rate of hairlessness in people. Is this result useful to say whether product X causes loss of hair? What arguments or experiments could you use to determine if X and loss of hair have a casual relationship?”

It is a very open ended question, I wanted to pick at my student’s brain and gauge how much of the class they assimilated more than I wanted an exact answer with an exact score (there were other questions for that). The results were very interesting.

As for the first part of the question, a very large number of students in all classes misunderstood the meaning of the word “useful”. They would answer that either the correlation does not prove the causation, which is correct, but is not what I was asking. Of course correlation does not prove the causation, the question itself states that! But still, it is useful information, because if the correlation was 0, we could exclude a direct causation right out of the bat.

As for the second part of the question, many, many students suggested tests with control groups to test if the causation really exists. This shows a fundamental misunderstanding of either what control groups are really about, or what about what correlation really means. If you have already stablished a strong correlation between X and hair loss, the logical conclusion is that a control group that is not using X will not show hair loss. The control group will simply confirm the correlation we already know about, and teach us nothing about the causality (or lack thereof) of X and hair loss.

This is not exactly an easy question — even though it uses no numbers or asks for no formulas! — but since I said they could use arguments instead of experiments, they could suggest different X with and without causality relationship with hair loss, and compare them. For instance, they could say that X could be either an anti hair loss product (and the causality relation would actually be inverse in this case!) or a shampoo with a bad chemical balance (and in this case there would be a causal relation) - the “experiment” in this case would be to actually investigate X and how it relates to hair loss in chemical/biological terms, and not something as simple as “Do a Z-test/double blind test/whatever”.

Things to keep in mind for the next time around…

One idea that I really like, is that our brain works a lot like a muscle.

What I used to mean by this is that, just like a muscle, our brain needs exercise to develop itself. Just like to be able to run 5 kilometers you need to practice running 2 km, then 3km, then 4km every day, in order to be able to make logic arguments and understand them, you need to work on logic problems and questions, and keep your brain active.

And just like by making regular exercise you make your body stronger and generally healthier (and happier), by making regular mental exercises you also make your mind sharper, and yourself a more interesting person.

To sum it up, people use to think that intelligence and wits are something that either you have, or you don’t, and if you don’t you should just not think about it (ha!), while my argument is that we can and should practice our brains and critical thinking, and as we do it, the world will naturally become clearer and make more sense for us.

That said, recently I started to build a little bit more on the above analogy. I started to think about mental sugar.

We have evolved to find very highly caloric foods tasty, and crave for them. This is probably because in our hunter-gatherer times, food was scarce. It was beneficial to gorge yourself in highly caloric foods in order to compensate for the times when you couldn’t find any. However, nowadays due to technological and economical progress, sugar/fat/etc is really easily accessed by a large number of people. And thus we consume too much of it, with negative effects on our bodies and health.

Just in the same way, the excess of pre-digested information easily available works like sugar for our brain. Because in ancient times we needed to be alert to survive, our brains were rigged to give a lot of attention to things that are new and unusual. However today we have very easy access to a LARGE volume of bit-sized, easily digested news, one after another. So much that in fact we can eat the next piece of new information before we have had the time to fully digest the previous one. So much that not only news are available, but a variety of comments of all kinds to even the most banal kinds of news.

I don’t say this because I hate information and the internet age. Actually, I love it. But I started to notice that in recent months my thought process had grown fat and sluggish. I was absorving so much new info, in so little time, that I was losing the ability to generate new info myself. The sugar and fat where going straight through my saturated mental digestive system, much of it was being lost, and very little of it was becoming “muscle”.

Of course, bite sized pieces of curious media and discussions are tasty, and they are good and have their value. But just like with our non-brainy part of the body, they need to be consumed with moderation, balanced with “healthy” information (varied nutrients, need work and effort to be digested), and lots of mental exercise if you want to keep your brain in a good shape.

Easier said than done, obviously, but at least now I gave this problem a name and a shape.

A few weeks ago, I got from a Couchsurfer a pack of Kangaroo meat as a present. In the package, there was an illustration of a herd of Kangaroos in the wild. That got me thinking about one of the things I find most surreal in our world.

Have you ever noticed how many packages for animal-based foods, or restaurants which specialize in a kind of animal, often sport images of such animal in a happy or cartoonish way? Like the pork restaurant with a cute pig with a chef hat in the billboard, or the fried squid tents in Japan with a happy squid preparing the fried squid balls. Now, while I don’t object in any way to eating meat, these kind of illustrations are just creepy to me. I mean, the animals probably wouldn’t be too happy about being eaten, and certainly would not be preparing the food themselves. Really, it is just WRONG.

When my RPG player blood is strong, I often enjoy imagining counterpart scenarios, like festivals made by trolls and orcs where images of cute little boys or smiling women illustrate the tent where they sell snacks made of unlucky adventurers…

By the way, the Kangaroo meat was not that good, if you were wondering.

Today I woke up at 5:00AM because some Couchsurfers were leaving early to take a plane in Narita. Actually, I don’t mind it at all. I read some news on the net, put the trash out, and then after 1 hour went back to sleep.

When I went back to sleep, however, I actually started thinking about Sleeping. Sleeping is a fascinating function of most higher animals that we still don’t understand fully - what exactly is its function, how much sleep do we need, how it works. The second question in particular was grabbing my mind at the time.

How much sleep do we need? The common answer is about 8 hours of sleep per night for an adult. Some people live on 6 hours sleep routines (I did for a while). Yesterday, I went to bed around 1 in the morning, and, having woken up at 5, that puts me at 4 hours. Since I had no reason to stay awake, I decided to “fill my quota”, by sleeping another 2 or 3 hours before waking up for good.

But is it okay if we sleep 4 hours, stay awake 2, and then sleep another four? What about 4 hours sleeping, 4 awake, 4 sleep? What about breaking it in small intervals? Or one big 6 hour interval and three 1 hour intervals? I was thinking about that. I remembered a story about a famous scientist (was it Newton? or DaVinci?) who was said to live in a “sleep one hour, stay 3 awake” schedule (XKCD has a different suggestion). At these times I wish I had been a neurologist…

Eventually I went back to sleep, but now with the late spring sun rising early in the morning, I was up again by eight. Well, all the better for me to get to work, but now I must start taking care not to sleep too late if I want a full night of rest before the sun wakes me up

An interesting article where scientists compare the memorization abilities of chimps and humans - the test is to try and memorize a sequence of numbers that briefly flash across the screen.

http://news.yahoo.com/s/ap/20071203/ap_on_sc/chimp_memory_1

I wonder if the fact that humans try to process the meanings of the numbers affects the results. I hope that they also do a test where, instead of numbers, meaningless symbols are used.