Gas station without pumps

2018 November 16

New book cover draft

Filed under: Circuits course — gasstationwithoutpumps @ 18:11
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I did a slight redesign of the cover of my book with the tentative new title.  I’m not a graphics designer, so all I’ve come up with is a rather generic book cover:

Tentative new book cover

I’m open to ideas for better cover designs.

Other than the cover, I’ve been making decent progress on the book—I even got PteroDAQ recompiled for the FRDM-KL25Z board and Arduino boards, which I haven’t bothered with for a couple of years, as we’ve been using just Teensy LC boards in the class.  ( had to make some tiny fixes to the PteroDAQ code, but nothing that took more than a couple of minutes.

I’ve got 4 to-do notes left in the book, only one of which is important (including some theory of soldering).  The other three are all optional material which needs to be cleaned up a bit or thrown out.  I think I’m still on track for a release by Nov 30.

2014 January 14

Silly library labels

Filed under: Uncategorized — gasstationwithoutpumps @ 11:15
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As a school librarian, my wife often gets library supply catalogs (and orders from them). I was particularly struck by an offer in the latest Demco catalog:

The "modern genre labels" from Demco.

The “modern genre labels” from Demco, copied from

The first thing that struck me is that using the myth of the horned Viking helmet as an icon for history was not very respectful of the scholarship of historians.

Sorry about the low quality of this image—I zoomed in on the gif from Demco, as I did not have an original sticker to scan instead.

Sorry about the low quality of this image—I zoomed in on the gif from Demco, as I did not have an original sticker to scan instead.

The second thing that struck me was that the “modern” label for science fiction was similar to the labels used in the 1960s. I think I remember that fat rockets were used on spine labels in the 50s, but I couldn’t find an example on the web quickly. In any case, these labels would be better described as “retro” not “modern”.

If you look more closely, you’ll see that the artist made the “star-in-front-of-the-moon” mistake—probably deliberately to irritate science fiction readers.

Image copied (without permission) from

Old spine labels for science fiction. Image copied (without permission) from (more precisely from

The final straw was the e-book sticker. What exactly do you stick an e-book spine sticker to?

2011 July 4

Interactive Maps

Filed under: Uncategorized — gasstationwithoutpumps @ 15:45
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In recent months, I’ve noticed a growing trend for newspapers, government agencies, and think tanks to present data on interactive maps,which are a fun way to explore certain types of data.  Here are three recent examples:

An interactive map can be a very handy way to look at something that varies from place to place, but can be highly misleading, if the variation is due to some cause other than location.

For example, the broadband availability map claims to be about broadband availability for schools. I searched for Santa Cruz County and got a pretty map:

Broadband map from showing Santa Cruz County.

Unfortunately you have to drill down to the individual schools, clicking on each one, to find out that there is no data whatsoever about the connectivity of the schools. They have taken a map of what some (unspecified) vendors have claimed is available in the community and overlain it with the locations of the schools. The implied statement about the availability of broadband at the schools is pure conjecture.
This sort of interactive map, which seems to be providing one sort of data, while actually providing something else, is such bad data display as to border on fraud. An academic researcher who tried to publish something like that using a government grant would probably get investigated for scientific fraud (but the government’s own publications, produced at much higher cost, are not subject to any sort of review).

The New York Times has some strange things on their interactive map also. Because they treat all data in units of a county, the resolution of the map varies enormously. At 20,105 square miles, San Bernadino County has more area than 9 states (Rhode Island, Delaware, Connecticut, New Jersey, New Hampshire, Vermont, Massachusetts, Hawaii, and Maryland).

So the resolution of the map in California is terrible—does it matter?  The map makers intended for people to infer correlation (about metropolitan or rural unemployment, for example) from the map, and so provided selection for metropolitan areas. Note that the whole central valley, which is primarily agriculture, has been listed as a “metropolitan area”, because the total population of the large counties exceeds the NY Times cutoff—even Shasta County has been considered a metropolitan area.  This map is essentially useless for separating rural from metropolitan areas, and so the main correlation that the map-maker wanted us to see is essentially not possible (at least not in the large-county states—it may work in New York State, which is probably all that the map-maker thought about).

Map of unemployment in "metropolitan areas" in California, from the NYTimes interactive map.

Maps are useful for seeing geographic patterns, which sometimes lead to conjectures about causation. For example, combining the NY Time unemployment map with the Brookings Institute map of population age distributions leads to the question “Is unemployment low in the Great Plains, because everyone of working age has moved out?”

One of several images availabe from the Brookings Instiute interactive map.

Maps may be good for coming up with conjectures, but they are no substitute for scatter diagrams or histograms for following up on the conjecture.  Unfortunately, with some data at the state level, some at the county level, some at the Congressional District level, and some at the census tract level, it can be very difficult to put together convincing arguments from disparate data sources.

Luckily, as a blogger, I’m not responsible for creating such data analyses.

2010 November 28


Filed under: Uncategorized — gasstationwithoutpumps @ 00:07
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This post is not a list of tips for producing slides to support a presentation (maybe I’ll do a post on that some other time).  Instead, it is a reflection on a pair of essays by Edward Tufte and Jean-Luc Doumont.

I read and enjoyed Edward Tufte’s essay The Cognitive Style of Powerpoint: Pitching Out Corrupts Within. It is a hard-hitting critique of the “pitch culture” that turns all presentations into a series of bullet lists. I wanted to require it for my fall senior design class (which is largely about “soft” skills, such as team formation, management, verbal presentation, and writing), but I had a hard time justifying making the students pay $7 for a 32-page essay. Instead I required the free 6-page excerpt from the essay on Tufte’s web site that catches some of the main ideas, though it is not as well-crafted as the complete essay.  One of the main points that Tufte makes is that the choppy, bullet-list format encouraged by slides is destructive to longer narratives and connected thoughts, and that sentences and paragraphs are not evil.  Not in the excerpt is Tufte’s analysis of the spoof of the Gettysburg Address by Peter Norvig.

Edward Tufte is famous for his self-published books, particularly the first one, Visual Display of Quantitative Information, which is perhaps the best book around on presenting data graphically.  It should be required reading for every scientist, math teacher, science teacher, and journalist.  Edward Tufte also gives one-day workshops based on his books.  I’ve never been to one, but some of the grad students in my department have (Tufte gives a huge student discount: they get the seminar plus four of his books for just the price of the books).  The students report that he gives awesome seminars also, well worth the time and the money.

So Tufte’s credentials as a presenter of data are very, very solid, and people paid a lot of attention to his polemic against PowerPoint.  Perhaps too much so, as his criticism seems mainly directed at the use of slides to replace tech reports, which they clearly cannot replace.

Jean-Luc Doumont has written a good rebuttal to Tufte: “The Cognitive Style of PowerPoint: Slides Are Not All Evil” (Technical Communication, 52(1), 64–70, Feb 2005), which Amazon sells for $6.  Doumont also gives a good seminar on presentation (I’ve heard the one-hour version), and so I respect his opinions also. I got permission from Doumont to distribute his rebuttal to Tufte to my class, but I put it up on a secure server behind password protection. It seems that other teachers either asked for more permission, or have less respect for authors’ copyrights, as the PDF file can be found on-line with a Google search (and not at Doumont’s own website, where it would be if he had truly meant for it to be distributed freely).

Doumont’s main point is that Tufte missed the point of slides:

Three commonsense considerations related to purpose thus invalidate much of Tufte’s case against the use of slides:

  • Oral presentations typically have a different purpose than written documents (different even than companion documents).
  • Slides in oral presentations are viewed while the presenter is speaking, not read in silence like written documents.
  • Tables and graphs, too, may serve a range of purposes, from analysis by oneself to communication to an audience.

The slides should support the speaker, not replace him or her. Both authors agree that (in Doumont’s words) “presentation slides do not double up effectively as [a] presentation handout,” because what is effective as a presentation aid is too terse to be of much use as a standalone document, and a useful standalone document is too wordy to be of much use as a presentation aid. I teach students that the purpose of an oral presentation is as an advertisement for the written document: to make the listeners aware of the ideas and interested enough to want to know more.  There should be just a handful of take-home messages from an oral presentation—trying to pack all the information of a detailed technical paper into a talk results in the listener coming away with nothing.

Doumont also criticizes Tufte for conflating the tool PowerPoint and the slides produced with it—many of the bad things Tufte points out are the fault of the presenters, not of the tool they used. His criticism here is perhaps a little too protective of Microsoft, as some of the common flaws that Tufte points out are indeed encouraged by the tool (PowerPoint provides many very bad templates).  Still, Doumont’s point is well-taken: it is possible to do good presentations with PowerPoint, even if it is not as easy as making bad ones.

Note: to create his own presentations, Doumont does not use PowerPoint, but uses \TeX with an idiosyncratic macro package, not a style many people will find easy to copy.  I also use \TeX, with the prosper package in \LaTeX, using Adobe Reader to present the resulting PDF files.  This is the only way I’ve found to include decent math formulas in presentations, something I often need to do.  (There are other \LaTeX slide styles, but I’ve been reasonably happy with prosper, and I was not at all happy with the original SliTeX program.)

2010 August 22

Cool interactive visualization

Filed under: Uncategorized — gasstationwithoutpumps @ 06:03
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I’m usually more fond of static graphics than interactive ones for scientific visualization.  A good graphic has a particular story to tell, and the creator of the graphic should put some effort into figuring out the best way to view the data to make that point.  Sometimes a single view does not suffice to make the point clearly, and something more interactive is needed.  This is often the case for 3D protein structures, so presentations often use a molecular viewer with highlighting provided by the author.  (There is a collection of such images using jmol as the viewer on proteopedia, though I find the server access and download time so long that I rarely bother to go there, especially as only a small fraction of the protein structures have hand-done scripts for making a specific point.)

I recently came across a different interactive graphic that clearly presents a complex data set that would be hard to capture in a single picture.  It shows the age distribution of different countries at different times, and has been set up to compare different countries.  It is rather cool to move the year slider and see the baby-boom generation as a pulse in the (US) distribution moving forward and dissipating.  In other countries, the baby boom is a little later than in the US, and not dissipating as much.  Indeed, in Italy the peak of the baby boom is about 7 years later and there is enormous drop in the birth rate after then baby boom.  For exploration, I would have liked to be able to superimpose different years, and not just different countries, but this graphic is surprisingly effective at showing the differences in population structure in different countries (though data from some of the less developed countries would have been useful for comparison).

The change in the US population structure and the projections for how that population structure is expected to change for the next 40 years do suggest that we are likely to need to make some modifications to Social Security, as the fraction of the population past retirement age is growing rapidly.  The least disruptive change would be to raise the retirement age gradually, so that roughly the same fraction of the population remains in the workforce.

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