Our yard was in various stages of "work-in-progress" over the past years. The deck needed repainting so a lot of the cross-hatching that covered the underneath was removed. I was also regrading parts of the yard using dirt from under the deck.
Our neighbor complained that it was unsightly to see all the stuff we stored under the deck and would we please cover it back up again?
Hmmm.... Would they object to the following?
1. We're thinking of ripping some back seats off some junked cars and using them as patio furniture.
2. The Garden Gnome Liberationists are planning to use our yard as temporary storage.
3. The passenger rail car we ordered will be arriving next week and we're planning to use it as storage.
I'm waiting for them to complain about our compost bin. Perhaps its time to build a high fence.
Thursday, April 8, 2010
H1N1 vaccine price comparison
When I got my H1N1 vaccine shot several months ago, I did some comparison shopping via the kids experiences (at their doctor's office and the visiting nurses association that came to their school).
Pediatrician's office $35
Visiting Nurses Association $25
CVS Minute Clinic $15
It may even make David Goldhill proud.
Pediatrician's office $35
Visiting Nurses Association $25
CVS Minute Clinic $15
It may even make David Goldhill proud.
Toilet performance
We were in the market for a new toilet last month and stumbled upon this report on how well toilets flushed (which is now in its 16th edition!). We found it useful - it's too bad that we couldn't really try it out in the showroom so the report was the second-best solution.
Tuesday, April 6, 2010
Lindsey, Lindsay
While watching the Winter Olympics I thought I heard the name over and over again and wondered at its popularity (see previous post on baby names).
The SSA gives me two variants of the name and their rankings:
The SSA gives me two variants of the name and their rankings:
| Year of birth | Lindsay Rank | Lindsey Rank |
| 2008 | 380 | 277 |
| 2007 | 316 | 226 |
| 2006 | 263 | 186 |
| 2005 | 240 | 162 |
| 2004 | 241 | 146 |
| 2003 | 260 | 132 |
| 2002 | 255 | 122 |
| 2001 | 210 | 105 |
| 2000 | 179 | 103 |
| 1999 | 169 | 96 |
| 1998 | 161 | 97 |
| 1997 | 149 | 95 |
| 1996 | 133 | 86 |
| 1995 | 125 | 81 |
| 1994 | 107 | 69 |
| 1993 | 88 | 56 |
| 1992 | 81 | 57 |
| 1991 | 77 | 52 |
| 1990 | 69 | 51 |
| 1989 | 63 | 48 |
| 1988 | 57 | 48 |
| 1987 | 49 | 41 |
| 1986 | 46 | 39 |
| 1985 | 40 | 37 |
| 1984 | 36 | 35 |
| 1983 | 37 | 35 |
| 1982 | 39 | 40 |
| 1981 | 47 | 58 |
| 1980 | 71 | 91 |
| 1979 | 88 | 113 |
| 1978 | 95 | 152 |
| 1977 | 110 | 193 |
| 1976 | 134 | 267 |
| 1975 | 396 | 498 |
| 1974 | 691 | 647 |
Math based vs rule based
The few books that I've been reading here and here triggered some thoughts about economics and economic models.
1. Economics is as susceptible to fads just as all fields are. When I was in graduate school Sergio Rebelo taught a very popular growth theory class - so popular in fact that as graduate students around 20 of us clustered around the door of the classroom waiting for the class that came before us (an undergraduate class which I don't know what it was) to be over.
Once, the door opened and a young woman gasped at the crowd in front of her and inquired as to what the class was (that was obviously so popular). "Growth theory," someone beside me replied. "What? Gross theory?". We all laughed. "No, no. GROWTH."
In retrospect, maybe gross was a good word to describe the state of growth theory today. Even though it was based on "microfoundations" the implications and its mechanics are too gross to describe the empirics of growth. Back then, countless papers were being generated based on Solow's growth model, extensions of Grossman (yet another gross!) -Helpman and Romer among others. Where is growth theory now? What are the current fads?
2. Back then another fad was DSGE modeling and its offshoot, heterogenous DSGE models (Greenwood, Krusell, Smith, Den Haan, among others). These models were all math based, in particular, they were based on dynamic programming and rested on assumptions of convexity, compactness and continuity. In looking at the dynamics of distributions, ergodicity either had to be assumed or derived.
Despite the limitations of rule-based models as evidenced in the Poundstone book outlined above there is still some hope for these models and its close cousing agent based models. The problem with these models (as was clear in the book) is the somewhat arbitrary starting points that are assumed. (Some may argue that assumptions of convexity and continuity are somewhat arbitrary as well, but mainstream economists probably would not. Or would they?) The same criticism is directed at math based models that have chaotic dynamics.
What reason is there to prefer one starting configuration over another? I would argue that the starting configuration is dictated by the outcome of that configuration. How closely does it match the data? This is not unlike calibrated DSGE models that attempt to replicate the empirical data ("moment matching"). DSGE models would claim to be more "scientific" in that they are "calibrated" independently. Or are they? Many models that I have seen in the past usually had one "free" parameter that the economist could "play" with - one such parameter is the risk aversion parameter. Various values of this parameter would then be used (as "sensitivity analysis") to match the data.
The success of DSGE models has not been surpassed by agent based models and it is perhaps due to the fact that the latter is generally not looked upon as "classical" economics. As such some of the brighter minds that could have made progress in this field have been diverted to more mainstream economics. This is similar to what A. Zee described in the quantum field versus string theory choice that faced graduate students in his day.
One outcome is a hybrid agent math based model where some agents follow rules ("rule-of-thumb" consumers who consume all their income) while others follow some kind of optimization rule. This is the model of Campbell and Mankiw and is already in use. Yet, I think that these models do not go far enough. The advantage of rule-based models is that there is no need to assume convexity or continuity. In fact, it would be more interesting to see what would happen if this were in fact the case. After all, even though time is continuous we do not make decisions in continuous time. We consume discrete amounts and make rule-based decisions - e.g. refinance when interest rate hits x percent (as opposed to a math based rule that would prescribe x.ab percent).
The future of economics and economic models is also dependent on the tools that are available to them. For instance, Einstein was not able to formulate the general theory of relativity without differential geometry or tensor calculus. String theory depended on non-Euclidean geometry. These pure mathematics fields were already on hand to be adopted by physicists for their use. Yet their adoption depended on a few who had the vision to see these tools as being useful.
Does economics suffer from a lack of vision - that vision thing - to use different tools besides dynamic programming and differential equations? Or does it suffer from a lack of tools?
1. Economics is as susceptible to fads just as all fields are. When I was in graduate school Sergio Rebelo taught a very popular growth theory class - so popular in fact that as graduate students around 20 of us clustered around the door of the classroom waiting for the class that came before us (an undergraduate class which I don't know what it was) to be over.
Once, the door opened and a young woman gasped at the crowd in front of her and inquired as to what the class was (that was obviously so popular). "Growth theory," someone beside me replied. "What? Gross theory?". We all laughed. "No, no. GROWTH."
In retrospect, maybe gross was a good word to describe the state of growth theory today. Even though it was based on "microfoundations" the implications and its mechanics are too gross to describe the empirics of growth. Back then, countless papers were being generated based on Solow's growth model, extensions of Grossman (yet another gross!) -Helpman and Romer among others. Where is growth theory now? What are the current fads?
2. Back then another fad was DSGE modeling and its offshoot, heterogenous DSGE models (Greenwood, Krusell, Smith, Den Haan, among others). These models were all math based, in particular, they were based on dynamic programming and rested on assumptions of convexity, compactness and continuity. In looking at the dynamics of distributions, ergodicity either had to be assumed or derived.
Despite the limitations of rule-based models as evidenced in the Poundstone book outlined above there is still some hope for these models and its close cousing agent based models. The problem with these models (as was clear in the book) is the somewhat arbitrary starting points that are assumed. (Some may argue that assumptions of convexity and continuity are somewhat arbitrary as well, but mainstream economists probably would not. Or would they?) The same criticism is directed at math based models that have chaotic dynamics.
What reason is there to prefer one starting configuration over another? I would argue that the starting configuration is dictated by the outcome of that configuration. How closely does it match the data? This is not unlike calibrated DSGE models that attempt to replicate the empirical data ("moment matching"). DSGE models would claim to be more "scientific" in that they are "calibrated" independently. Or are they? Many models that I have seen in the past usually had one "free" parameter that the economist could "play" with - one such parameter is the risk aversion parameter. Various values of this parameter would then be used (as "sensitivity analysis") to match the data.
The success of DSGE models has not been surpassed by agent based models and it is perhaps due to the fact that the latter is generally not looked upon as "classical" economics. As such some of the brighter minds that could have made progress in this field have been diverted to more mainstream economics. This is similar to what A. Zee described in the quantum field versus string theory choice that faced graduate students in his day.
One outcome is a hybrid agent math based model where some agents follow rules ("rule-of-thumb" consumers who consume all their income) while others follow some kind of optimization rule. This is the model of Campbell and Mankiw and is already in use. Yet, I think that these models do not go far enough. The advantage of rule-based models is that there is no need to assume convexity or continuity. In fact, it would be more interesting to see what would happen if this were in fact the case. After all, even though time is continuous we do not make decisions in continuous time. We consume discrete amounts and make rule-based decisions - e.g. refinance when interest rate hits x percent (as opposed to a math based rule that would prescribe x.ab percent).
The future of economics and economic models is also dependent on the tools that are available to them. For instance, Einstein was not able to formulate the general theory of relativity without differential geometry or tensor calculus. String theory depended on non-Euclidean geometry. These pure mathematics fields were already on hand to be adopted by physicists for their use. Yet their adoption depended on a few who had the vision to see these tools as being useful.
Does economics suffer from a lack of vision - that vision thing - to use different tools besides dynamic programming and differential equations? Or does it suffer from a lack of tools?
What I've been reading
1. The Partition by Yasmin Khan
This is the only book I've looked at on the partition of India and Pakistan. The focus is mainly on the events a year before and after the Radcliffe line. The author offers her interpretation of some specific events that occurred during this time which I thought was interesting. Alas, I was looking for a grander insight - why after years of living together for so long was there so much violence? This question is also relevant for the ethnic violence in the Balkans after the collapse of Communism. In all, an interesting book but not quite what I was looking for.
2. The Recursive Universe by William Poundstone
This one was disappointing. The rule based "theory" for lack of a better word, is an alternative to the mathematics based laws of the universe. Unfortunately, it was not very coherent in tying together why a rule based universe is a contender to the math based universe. Most of the book seemed to cover various patterns that are the outcomes of Conway's Game of Life. Interesting if you are looking for a book that introduces the Game of Life and the various replicating patterns that can result but otherwise not.
3. An Old Man's Toy by A. Zee
This was surprisingly readable - probably the clearest description of gravity and the first few minutes of the Big Bang I've come across so far. If I had the time this would be worth a re-read. The author also relates his personal experience - choosing to specialize in quantum field theory at the time instead of string theory. The field of physics self selects in the same way that many fields do. Specializing in string theory at the time would have been academic suicide job-wise and the author chose not to take that path. Of course string theory is now having its day. See this post for my take on Paul Halpern's The Great Beyond which was readable until the part on tensor calculus.
This is the only book I've looked at on the partition of India and Pakistan. The focus is mainly on the events a year before and after the Radcliffe line. The author offers her interpretation of some specific events that occurred during this time which I thought was interesting. Alas, I was looking for a grander insight - why after years of living together for so long was there so much violence? This question is also relevant for the ethnic violence in the Balkans after the collapse of Communism. In all, an interesting book but not quite what I was looking for.
2. The Recursive Universe by William Poundstone
This one was disappointing. The rule based "theory" for lack of a better word, is an alternative to the mathematics based laws of the universe. Unfortunately, it was not very coherent in tying together why a rule based universe is a contender to the math based universe. Most of the book seemed to cover various patterns that are the outcomes of Conway's Game of Life. Interesting if you are looking for a book that introduces the Game of Life and the various replicating patterns that can result but otherwise not.
3. An Old Man's Toy by A. Zee
This was surprisingly readable - probably the clearest description of gravity and the first few minutes of the Big Bang I've come across so far. If I had the time this would be worth a re-read. The author also relates his personal experience - choosing to specialize in quantum field theory at the time instead of string theory. The field of physics self selects in the same way that many fields do. Specializing in string theory at the time would have been academic suicide job-wise and the author chose not to take that path. Of course string theory is now having its day. See this post for my take on Paul Halpern's The Great Beyond which was readable until the part on tensor calculus.
Monday, April 5, 2010
Sweeping up pennies
This is not the LTCM strategy of using leverage to suck up pennies but literally! I was at the line in McDonalds one day and saw a cleaner sweeping up pennies into his trash receptacle. If I had seen the pennies first, I probably would have pounced on them. After all, the kids in school were participating in Greg Mortenson's Pennies for Peace campaign.
It is strange to think that our society is so wealthy now that even a cleaner will not pick up pennies for himself. Certainly, a panhandler would even refuse pennies these days - it's not "brother can you spare a dime" these days but "brother can you spare a dollar".
It is strange to think that our society is so wealthy now that even a cleaner will not pick up pennies for himself. Certainly, a panhandler would even refuse pennies these days - it's not "brother can you spare a dime" these days but "brother can you spare a dollar".
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