Sunday, January 29, 2006
Causal Relationship
In numerous discussions with my roommates, I have held that I like research in physical sciences because it heavily depends on deduction rather than induction like life sciences (which interests them). In physical sciences, once you know the universal laws you can reliably and accurately predict the behavior of any system; knowing the general rule you can apply it to a specific instance. And the laws or rules are derived from a relatively few postulates, making study of physical sciences less memory intensive. The 'truth' in physical sciences is deterministic, or atleast has a steady state probability distribution. On the other hand, life sciences (like behavioral & social sciences) make a large number of observations and tend to generalize them to a rule based on statistical induction. Thus, the 'truth' is rarely deterministic, and many times has a dynamic distribution, with the probabilities changing with each new study.
A few days back I was complaining to a friend about my back pain. I said it must be because I am not getting enough sleep and rest. He said, my not getting sleep (Y) must be caused by my thinking about something (X) (he actually said somebody :-)) I had also reached the same conclusion independently, but since he put it in words I saw a flaw in the reasoning. Based on observations, everytime I can't sleep Y, I think of X. Thus, there is high correlation between X & Y, but can we conclude that X causes Y? It is equally possible that since I can't sleep and have nothing better to do I think of X. Is there anyway in which we can prove a causal relationship between X & Y? For all we know, both X and Y may be caused by a third variable Z (e.g. age), resulting in high correlation between X & Y. All we can do is notice the correlation and speculate on the causes. We cannot even reliably say whether the cause of insomnia is psychological or physiological. The same argument applies to sleep and back pain - we cannot say which causes the other. Thus, proving causal relationship (what is called "kaarya - kaaran siddhanta" in sanskrit) is a major pitfall in life sciences, making its discoveries as speculative and reliable as price discovery in stock markets.
A few days back I was complaining to a friend about my back pain. I said it must be because I am not getting enough sleep and rest. He said, my not getting sleep (Y) must be caused by my thinking about something (X) (he actually said somebody :-)) I had also reached the same conclusion independently, but since he put it in words I saw a flaw in the reasoning. Based on observations, everytime I can't sleep Y, I think of X. Thus, there is high correlation between X & Y, but can we conclude that X causes Y? It is equally possible that since I can't sleep and have nothing better to do I think of X. Is there anyway in which we can prove a causal relationship between X & Y? For all we know, both X and Y may be caused by a third variable Z (e.g. age), resulting in high correlation between X & Y. All we can do is notice the correlation and speculate on the causes. We cannot even reliably say whether the cause of insomnia is psychological or physiological. The same argument applies to sleep and back pain - we cannot say which causes the other. Thus, proving causal relationship (what is called "kaarya - kaaran siddhanta" in sanskrit) is a major pitfall in life sciences, making its discoveries as speculative and reliable as price discovery in stock markets.
Saturday, January 14, 2006
Adding teeth
Some people believe that the biggest problem in India is its toothless laws. Often comparisons are made with the western countries to show the disparity in legal penalties for the same offence. e.g. A traffic violation carries a penalty of only Rs. 50 (approx. $1) for a two-wheeler and Rs. 100 ($2) for a four-wheeler. Or, the mean penalty (fines & damages) for environmental violations in USA from 1980-2000 was $8.8 million (another study - $9.43 million), while in India all a pollution control board might do is lock up the violating unit.
With all the calls to add more teeth to laws, and strongly believing in "being the change you want to see", I decided to take immediate action. Hence, I added more teeth, 3.75 to be exact.
My teeth have been a constant source of amazement and amusement for people since years. The two upper incisors were the most conspicuous by their absence. My parents, alarmed when the teeth failed to appear a long time after the normal age, visited many dentists without any success. All of them failed to notice that Nature had more than compensated me in some other part of the skull for this deficiency. Since I was observing silence at that time I couldn't remind them that God giveth and God taketh away, and in my case there was so much less for God to take away. With respect to the gaps between my teeth, being 'susanskrit', my parents took comfort in the sanskrit saying: "How many bald men are poor, How many singing women are sati, How many dantaala (a person with large gaps between teeth) are unlucky, Very few, Very few".
However, three years back I lost one more teeth (that story is given below) and was left with only 1.25 incisors instead of the regular 4. The surviving incisor, instead of rejoicing on being the only one - 'the one' - like Neo, started complaining and even threatened to quit the job by slowly moving outwards with ambitions to see the vast world outside. However, I was undeterred by all these, and decided to add more teeth only with the noble intentions outlined in the first few lines.
I have chronicled below the story of the premature demise of a young tooth, for the benefit of posterity.
Date: Sat Nov 16, 2002 7:43 pm
Subject: from proud owner of 19 teeth
hi
hope everybody had a happy diwali.
for me this diwali will be the most memorable one.
i lost one of my several (more than 20!!) teeth on diwali.....
i had gone to ooti with two other ppl. its about 100 kms. we had a very nice time. ooti is really great place....
on the second day (diwali) at one of the waterfalls i slipped on a stone and lost one tooth. my boss and colleagues here believe that i fell becoz i got drunk. that tells something about the reputation ooty and i enjoy.
well, romy i will be here when u come in december. especially to show u some of the very interesting sign boards in coimbatore. for example
1. when u see a board 'Yes Pee Yes Co.', don't think its a southern counterpart of Sulabh International. its not a urinal. the name is derived from its owner whose initials are SPS.
2. there is a Maruti service station with a board visible from half a kilometer saying 'Maruthee Service station'. thankfully it also has the maruti logo to help outsiders.
3. 'Tiching charge' means tution fees. (teaching)
4. There is a two storeyed building proudly declaring itself 'S B Towers'
and this is just tip of the proverbial iceberg.....
With all the calls to add more teeth to laws, and strongly believing in "being the change you want to see", I decided to take immediate action. Hence, I added more teeth, 3.75 to be exact.
My teeth have been a constant source of amazement and amusement for people since years. The two upper incisors were the most conspicuous by their absence. My parents, alarmed when the teeth failed to appear a long time after the normal age, visited many dentists without any success. All of them failed to notice that Nature had more than compensated me in some other part of the skull for this deficiency. Since I was observing silence at that time I couldn't remind them that God giveth and God taketh away, and in my case there was so much less for God to take away. With respect to the gaps between my teeth, being 'susanskrit', my parents took comfort in the sanskrit saying: "How many bald men are poor, How many singing women are sati, How many dantaala (a person with large gaps between teeth) are unlucky, Very few, Very few".
However, three years back I lost one more teeth (that story is given below) and was left with only 1.25 incisors instead of the regular 4. The surviving incisor, instead of rejoicing on being the only one - 'the one' - like Neo, started complaining and even threatened to quit the job by slowly moving outwards with ambitions to see the vast world outside. However, I was undeterred by all these, and decided to add more teeth only with the noble intentions outlined in the first few lines.
I have chronicled below the story of the premature demise of a young tooth, for the benefit of posterity.
Date: Sat Nov 16, 2002 7:43 pm
Subject: from proud owner of 19 teeth
hi
hope everybody had a happy diwali.
for me this diwali will be the most memorable one.
i lost one of my several (more than 20!!) teeth on diwali.....
i had gone to ooti with two other ppl. its about 100 kms. we had a very nice time. ooti is really great place....
on the second day (diwali) at one of the waterfalls i slipped on a stone and lost one tooth. my boss and colleagues here believe that i fell becoz i got drunk. that tells something about the reputation ooty and i enjoy.
well, romy i will be here when u come in december. especially to show u some of the very interesting sign boards in coimbatore. for example
1. when u see a board 'Yes Pee Yes Co.', don't think its a southern counterpart of Sulabh International. its not a urinal. the name is derived from its owner whose initials are SPS.
2. there is a Maruti service station with a board visible from half a kilometer saying 'Maruthee Service station'. thankfully it also has the maruti logo to help outsiders.
3. 'Tiching charge' means tution fees. (teaching)
4. There is a two storeyed building proudly declaring itself 'S B Towers'
and this is just tip of the proverbial iceberg.....
