Paul Krugman, Princeton economics professor, winner of the Nobel prize in economics for 2008 and New York Times op-ed writer is a person worth paying some attention to. Unlike most other mainstream commentators he does not deal mainly in cliches and often shows respect towards his readers by supporting his positions with hard data. He is also willing to take some risk by, on occasion, pushing against the envelope of mainstream propriety and using impolite words toward people with power.

Of course, he is not without faults. Of course, none of us is. The point is that Krugman’s faults are not too different than those of many of his colleagues. In other words, while Krugman is somewhat of an exquisite specimen of the mainstream intellectual, he is still very much such a specimen.

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The Consumer Expenditure Survey (2007 data) shows (1, 2) that the higher a household’s income is, the more its members travel. Households whose income is above $150,000 a year spend on average about $4,000 a year on gasoline and motor oil, while household whose income is under $15,000 a year spend about $1,000.

The BLS groups air travel together with cruiseboat travel and mass transit under the heading “public transportation”. Most of the amount under this heading is spent on air travel, with the proportion increasing with income. The amount spent on “public transportation” is therefore a good indicator of the distance covered in travel by air, and inequalities in the expenditure in this category can serve as lower bounds for the inequalities in air travel. The expenditure within this category is overwhelmingly by the rich. The top 10% of households account for about half of the total expenditure on “public transportation” – a proportion similar to their share in the total income.

Dishwashing: man vs. machine

September 24, 2008

When searching online for information comparing manual dishwashing to dishwashing machines, a University of Bonn study is the most prominent point of empirical research that shows up (e.g., 1, 2, 3, 4). This study is usually interpreted as showing that dishwashers are more resource efficient than hand washing – using less work time, less energy and less water to wash the same amount of dishes.

Some commenters in the Treehugger post linked above showed healthy skepticism of this all-too-convenient claim. Fortunately reports from the University of Bonn study are available online (1, 2, 3) and the researchers were kind enough to include some data in those reports, making it possible to examine the results rather than rely on media reports alone. I thus decided to have a methodical look at the study – this post presents my conclusions on this matter.


Multiple weaknesses in the experimental setup make the interpretation of the study difficult. The data analysis carried out by the researchers seems tendentious. Claims that the study shows that using a dishwashing machine saves substantial amounts of energy, water and time as compared to hand washing are highly dubious. According to the study’s own findings, the most efficient handwashers used far less energy (actually, none, since these washers used no hot water) and about the same amount of water as the most efficient machines. Using no hot water had no negative impact on the cleanliness of the washed dishes.

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Data source: Energy information administration, End-Use Consumption of Electricity 2001, Residential Energy Consumption Survey.

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Data source: BTS National Transportation Statistics, Table 4-6.

Data: Gasoline price, household count and median household income (Table H-5), consumption of gasoline

Update (Sept 1st, 2008): image updated to show 2007 data.
Update (Sept 10th, 2009): image updated to show 2008 data.
Update (Nov 2nd, 2010): image updated to show 2009 data.

Energy consumption per capita in the U.S. is about 10 Kilowatt. For illustration, the power consumption of the human body is about 100 Watt (2000 Kilocalories per day) . That is, each person in the U.S. consumes on average 100 times more energy than that which is required for sustaining his or her body. Another point of reference is that 10 Kilowatt per person is what a family of four would be using if it would be driving its car on the highway for 14 hours a day (every day – 365 days a year).

The per-capita power consumption level has not changed much since the early 1970s. While energy use for residential, commercial and transportation purposes have been rising (at the rates of about 0.2%, 1.2% and 0.5% per year, respectively, on average), these were offset by a reduction in the consumption in industry (by about 0.8% per year on average).

Update (Feb. 2009): Updated links and data for 2007 (2009 Abstract).
Update (Feb. 2010): Updated links and data for 2008 (2010 Abstract).
Update (March. 2011): Updated links and data for 2009 (2011 Abstract), and extending data back to 1900 (Data source: Statistical Abstract of the U.S. 1960, Table 686). Consumption data is available back to 1920 (marked by ‘c’), production back to 1900 (marked by ‘p’).

Epistemology omnibus

February 22, 2008

This omnibus post collects draft fragments that are associated with the economy of attention and the sociology of science and expertise.

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Looking back, looking ahead

February 6, 2008

This post is aimed at serving as something of a self evaluation of the first 6 months of this blog, and a statement of intent for its future.

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Display power consumption

February 1, 2008

Abstract: LCD TVs are about as power efficient (i.e., they consume about the same amount of power per square inch of display area) as CRT TVs. Thus a 50″ LCD TV consumes about 4 times as much power as a 25″ CRT TV. However, LCD monitors are 2 to 3 time more power efficient (i.e., consuming 2 to 3 times less energy per square inch of display area) as CRT monitors.

During a discussion about the popularization of large screen TVs, the claim was made that LCD TVs are much more power efficient per square inch than CRT TVs, largely offsetting the rise in display area to maintain a more-or-less constant total power. I was prompted to try to find information about the matter over the web.

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