Smoke Detector Stats

Busy, busy, but I have to take up an obvious piece of faulty reasoning here. An opinionator in the Swedish daily paper Dagens Nyheter by the name of Malin Siwe has a short piece arguing against excessive safety regulations. It's not really unusually bad; indeed, that's my problem with it. This is rather typical for newspaper opinion pieces, in fact.

She is trying to make a perfectly good point: when safety rules become too numerous and too detailed, people end up trying to comply with the rules rather than actually improving safety. The problem with the piece is that her main example is an argument in favour of more rules, not against it. And her lack of statistical understanding means she is completely oblivious to that fact. Here's the relevant passages (roughly translated, emphases mine):

All apartment buildings built since 1999 must have smoke detectors. Many local governments rule that all homes must have them installed. Nine out of ten households have such smoke detectors today.

...

Most cases [of deadly home fires] lacked a smoke detector, but they were there in a large minority of cases - and some worked.

She's arguing that smoke detectors don't help, and that a law mandating them everywhere wouldn't do any good. But she is innumerate enough that her example is actually arguing against her position. Now, can anybody spot the problem above? The information in bold is enough to figure it out.

90% of homes have smoke detectors and 10% do not. Now, if smoke detectors really were useless, then 90% of the fatal fires would also happen in smoke detector-equipped homes while 10% would happen in detector-less ones. But they don't. As she says, a "large minority" of fatal cases happened when a smoke detector was present. Even with a generous interpretation of "large minority", less than half of fatal fires happened when there was a smoke detector in the home.

Let's be very generous, in fact, and say that half - 50% - of fatal fires happened in homes with smoke detectors. In that case, you're nine times less likely to die if you have a smoke detector than if you don't. If "large minority had smoke detectors" actually is something like a third then the number is closer to 20 times. That, to me, is some very persuasive data in favour of mandating smoke detectors.

I don't have a background in statistics¹. I suck at this kind of reasoning, so I always need to draw a figure or two to really understand what is going on. Just to make it clear, take a look at the figures below:

The total area of the rectangle above is all the homes, smoke detector or not. The blue part - 90% - is the homes with a smoke detector. The small orange part at 10% are the homes without. We want to figure out how much more likely you are to have a fatal fire if you're in a home without a smoke detector.

Now we add the fires; that's the small rectangle straddling the two home areas. We don't know how many fires there are compared to the overall number of homes, but it doesn't matter. We're only interested in the difference in risk between smoke detector and detector-less homes.

We were generous above, and said that half the fires where in homes with smoke detectors. So half of the "fire" area is on the "smoke detector" side, and half on the "no detector" side. Again, the size of the "fire" area depends on how many fires there are, but the proportions don't change.

Now, note that the "fire"-part is a much bigger part of the "no detector" area than it is of the "smoke detector" area. That is the point - a much larger proportion of no-detector homes will have a fire than the proportion of smoke detector ones. You're much more likely to have a fatal fire without a smoke detector than when you do.

Let's make it clearer still: Here's the "no detector" area at the top, and the "smoke detector" area at the bottom. We've scaled them so we can compare them directly. Again, the "fire" area - the risk of having a fatal fire - is much larger for the detector-less homes than for those with a detector.

How large the risk is depends on the total number of homes and the number of fatal fires. But the difference in risk depends only on the proportion of smoke detectors, and the proportion of fires in those homes. With our numbers - 90% of homes have smoke detectors, and have 50% of the fires - it turns out you're nine times more likely to have a fatal fire when you don't have a detector than when you do.

Now, she points out that only some smoke detectors actually work. True enough - but that means a larger proportion of fires should be counted among households without smoke detectors too, and becomes an argument in favour of mandating smoke detectors and periodic checks, rather than against. Even with the most pessimistic estimate of working smoke detectors, you're still a couple of times more likely to avoid a fatal fire when you have one in your home².

For those who can't read Swedish she also has a rather confused line of argument around the total number of fatal fires, but it's so incomplete and specious that the only thing it shows is that she doesn't understand high-school level statistics.

Now, I don't blame her. She's not good with statistics - but then, most people are not. Nobody is good at everything. Where she goes wrong is not in misunderstanding statistics; it's in not asking somebody who does understand it for feedback and help.

This is why I despair over the future of the newspaper. After all, the defining difference between professionally staffed newspapers and bloggers is supposed to be that newspapers have the time, the resources and the know-how to check original sources, ask experts for second opinions, fact-check every word and edit the finished text. This opinion piece could have been sanity-checked in ten minutes by anybody with a basic mathematical background. No need to even go outside; somebody from the newspaper's Accounting or IT department would have enough math background to catch the faulty reasoning.

But it wasn't fact checked. As it is, the columnist has published a blog post an opinion piece arguing against the (otherwise quite reasonable) standpoint it was meant to support. When newspaper opinion and editorials ends up reading like second-rate blog posts, I'd rather just skip the papers and read first-rate posts on the net instead.

#1 To the occasional frustration of my coworkers.

#2 I don't know about you, but given the choice I'd rather not burn to death if I can help it. Fire safety is cheap compared to the consequences.

We have legally required smoke detectors, central fire alarm and sprinkler system throughout the apartment, a fire door in the corridor and an emergency ladder on the balcony. It is tested and checked once a year by a couple of fire-safety inspectors; we even get to activate the ladder and climb onto it if we want so we really know how it works. In addition we've added a small fire extinguisher in the kitchen near the gas stove, and we plan to add another one in the bedroom.

Living right on top of an active fault in an earthquake-prone country tends to focus your mind in these matters.

Observations On the Nature of Distance, As Occasioned By a Sushi Lunch

I realized something interesting about physical and mental distances today. A colleague from Slovenia is visiting ATR (my former workplace) for two weeks and we decided to get together for lunch. As it happens, ATR is in the same area as NAIST, my current workplace. Getting there is quite inconvenient, though.

First you walk from NAIST to the Kita Ikoma station. Wait for a train and take it (through a tunnel) to the next station over, Gakken-Nara Tomigaoka. From there you either walk or take a bus for Keihanna that leaves every half hour; they're not synced with the trains so you may or may not have to wait for quite a while. Half the buses go fairly direct, half take a scenic detour through the suburbs. All in all the trip takes a bit more than an hour. That's the red line in the map below.

NAIST on the center left, ATR upper right corner. Lower left is Kita Ikoma station, lower right is Gakken-Nara Tomigaoka. The long, red wiggly line is the path taken with train and bus. The short yellow line is by foot. An eagle-eyed observer may suspect that you can actually go straight across, making the distance even shorter; they would be right.

After lunch, with beautiful late summer-like weather (still over 20° here this year) and a stomach full of sushi, I decide it's a good idea to try to walk back, rather than take the train. And I discover that the whole distance takes all of 45 minutes - almost twenty minutes faster than taking the bus and train. That's the yellow line. In fact, the most inconvenient part, from NAIST to Gakken Nara Tomigaoka station takes only fifteen minutes to walk, the exact same time it takes to walk to Kita Ikoma. Taking the train this one stop is simply a waste of time and 200 yen. This is still a fairly roundabout route; you can go right across if you want, from village to village, and probably shave another ten minutes off that walking time.

I had a nice walk after lunch - so what? What's interesting to me is how wedded I've been to the idea that I have to go by train. When I worked at ATR I always took the train from Osaka, and I of course go to NAIST by train as well. So to me, they are isolated islands in my mental map, with no route between them except this "wormhole" or "gate" that is the train linking them to the rest of my world. ATR is part of Keihanna and Housono village where I lived for a couple of years; it's a fairly large area in my mind, with two separate train stations leading away from it. NAIST is a much smaller and more recent island with the Kita Ikoma station as the only exit.

So even with a map right in front of me I simply never really connected the areas in my mind. The only route I knew was via the train stations, so I've always taken the train without thinking about it. Now that I've walked across they're suddenly no longer separate islands, but one connected area. Of course, it's still an island, separate from Osaka on one hand, and Kyoto on the other since I've never really traveled between those areas either, just magically whisked between them by train.

To the left, my map before today's walk; to the right, afterwards. The lines are the "magic portals" - trains - connecting my mental areas. "Osaka" and "Kyoto" are of course really several disconnected maps in their own right. I could probably easily merge "saidaji" with ATR; I've just never had reason to actually go there by foot or bicycle.

One thing I wonder is what kind of transport will alter mental maps like this and what kind will not. Walking can obviously connect and merge areas like it did for me today, and I think bicycles do too. I'm not sure about cars and bikes when you drive; if you're a passenger I strongly suspect you don't.

Being in control rather than a passive observer is probably important (although there's a delightful old experiment by Tolman (I think) where rats wheeled around a maze in a cart do learn the maze without actually running in it). But as important, I suspect, is feedback on the distance you travel. One reason a train doesn't connect areas at all is probably because you get no feedback on how far you're actually going. When you walk or bicycle, you feel the distance directly. With motor transport you don't. In the diagram above I could probably add "Tokyo" right next to Kyoto with a magic line between them, and add "Okinawa", "Helsinki" and "Ho-Chi Minh"-areas via a small, separate "Kansai Airport" blob. They'd all be at the same mental non-distance between each other to me.

I'm sure there must be several studies about this. If I wasn't already buried neck-deep in other papers I need to read I'd go take a look. If anybody already has references about this, though, feel free to send them my way.

The Future of the Sports Car

Toyota is leaving Formula 1 racing. BMW has decided to quit next year, Honda left already last year, and Renault is reportedly considering leaving as well. Rally has seen losses of car company teams. Crisis for high-end racing, and it's not surprising during a severe economic recession of course, but there's perhaps more to it than that.

The generation-long rivalry between sports car maker Porsche and mass-market Volkswagen ended recently - and symbolically - with Volkswagen taking over Porsche outright (Ferrari is of course already a subdivision of Fiat). And Honda has stopped building sports cars altogether.

The muscle car - a dying breed? They are beautiful, though.

The sports car, the muscle car, the two-seater runabout, is - well, not disappearing, exactly; there's always going to be enthusiasts and car models that cater to them. But the era of the Fast Car is coming to an end.

The sports car has long been a small but serious market segment, important far beyond their sales numbers. They are aspirational cars, something to build your brand and lure people into your showrooms to buy one of your mainstream models. Think of how many teen-age boys have had a beloved poster of some sports car or another, and how many of those ended up getting a car from that same manufacturer when they grew older.

More people than ever have licenses and cars to drive. The car is still a very desirable item. But the nature of car ownership is changing. To more and more young people, a car is no longer a defining symbol of adulthood, and the interest in vehicles as a hobby is waning. Ask any motor club about how the median age of its members have changed over the past generation or so.

Also, the car itself is increasingly being viewed as a pollutant and as the main link still chaining us to the current oil-based economy that is increasingly seen as untenable in the long run. Instead, the cars that capture buyers imagination and grab press headlines are increasingly small and efficient cars, and the future-looking all-electric vehicles. A traditional sports car, with its thirsty engine and flashy looks, seems backwards-looking, a symbol of wastefulness as much as youthful fun. A sports car in your line-up no longer helps sell your ordinary cars; indeed, it may be a net negative.

And of course, with electric vehicles the impression of the car changes. It becomes more of an appliance, like your refrigerator, than a potent lifestyle symbol. A gasoline engine is an amazing Rube Goldberg-esque contraption of mechanical linkages and delicately balanced interactions. It is both very accessible to those who wish to tinker with it, and very temperamental, making it well worth tinkering with.

An all-electric system is different. It's far more even, more predictable and reliable, and any required tuning is done completely through software. Not that there's a huge scope for tuning; electric drive systems come pretty close to your theoretical performance limits right from the start. There's just not much fun in hacking an electric car, and plenty of high-voltage danger for anybody trying. The car hobby - car building and tuning especially - is going to have a hard time adapting to this change.

Pink car covers near Yotsubashi, Osaka.

Spreading lack of interest in muscle cars, the negative brand impression of selling thirsty, wasteful gasoline vehicles, the disproportionate cost of keeping up a high-end small-volume brand, and the lack of proper return on investment on very expensive racing programs - those are the reasons that sports cars are slowly disappearing and car makers are turning away from high-end motor sports. The current recession has just accelerated a change already on the way.

Elephant Time, Mouse Time

In my copious spare time¹ I'm reading another book after finally getting through "The devotion of suspect X"². This time I'm not doing a novel, but a non-fiction popular science book. It's a good change of pace, and as a bonus I get to practice some useful vocabulary you don't encounter in most fiction or news reporting.

The book is "ゾウの時間ネズミの時間ーサイズの生物学" ("Elephant time, Mouse time - the biology of size") by Tatsuo Motogawa. It's a look at how body size affects various aspects of animal life. The title itself suggests the overall theme: An elephant and a mouse have very different life spans, but their lives scale with size. A mouse has a much faster generation time, it moves and reacts much faster than an elephant - it must look hopelessly slow and ponderous to a mouse - and even their internal organs work faster. The mouse may end up doing as much as the elephant throughout its life so they live "as long", subjectively, even though the life span is very different.

 
There's chapters on energy use and food intake, how the size of prey versus size of predator, movement range and population density, cellular activity, speed, organ size and so forth. The book is not just about mammals either; it covers related differences between warm-blooded animals, insects, unicellular animals and water life versus land life as well.

At about 230 pages including appendices it's not a big, heavy book. I've read about a fourth of it so far and I find it both enjoyable and very accessible. There's a bit of specialized vocabulary of course (I'd find it disappointing if there weren't) but his style is clear and direct so it's not a problem. The math is minimal, and what there is, is clearly explained and presented. The appendices give more background for those who need or enjoy such things.

If there's one thing I find a bit annoying it's his occasional tendency to insert largely irrelevant observations on Japan in the text. This is something a fair number of Japanese writers seem to do, though; there's even a thriving publishing genre comparing Japan to other countries, always either doom-and-gloom negative or fiercely patriotically positive.

A less scrupulous blogger would probably spin long involved yarns about how this preoccupation reflects on the Japanese society and its insecurities (and so falling prey to the exact same phenomenon they try to analyze). Me, I don't think this is exceptional at all. Everybody loves to hear about themselves, and it's just the form of self-affirmation that differs. The simplistic "We're Special so We're #1!", "We're Special so We're Doomed!"-format is just one that resonates with part of the Japanese public. It's simply akin to when other people slap their flag on every available flat space, or obsessively compare athletic, technical or historical accomplishments with other countries.

These distracting detours aside - and in truth there aren't many of them - it is a fun book; engaging and inspiring enough that it makes me wish I'd studied ecology as a student. It doesn't seem to have been translated, but if you do know Japanese - or if you study it - you can certainly do much worse than to pick this one up at your local book store.

As an aside, this was published in the 中公新書 (chūkōshincho) book series. There's several series of small, inexpensive pocket books here that are either reprinting older works or publishing narrow-interest books like this one in various fields. This series seem to publish a lot of popular academic (science and the arts) and technical works. I've also bought - but not yet read - a biography on Euler, a work on insect neuroanatomy and a book by a retired JR train driver on the design and operation of railways³. They all seem very promising, so I'm not wanting for reading material once I finish this one.

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#1 My blessed half-hour of peace and solitude on the morning train. The evening ride is for studying Japanese.

Seriously, even ignoring the money - just the parking fees at home and work would almost reach my current monthly train cost - I wouldn't want to commute by car. This free time is too important to waste on driving.

#2 I know I wasn't very favourably impressed with it. But it turns out it may not completely be the books' own fault. I read it after finishing Reason by Miyuki Miyabe. Ritsuko is also reading another book now, after she finished a Miyabe book series, and she, too, finds that wanting, even though it's a book she should like. It may simply be that Miyabes works are so good that whatever you read afterwards becomes a let-down by comparison.

#3 Why yes, I am a geek. How did you guess?

November

It's the morning of November 1st. And outside it is, at this moment, 24 degrees.

Current value and today's curve in red, yesterday in orange. one-week averages for this week and this week last year in blue.

The winter may be wet and miserable in Osaka, but at least it's never long. This kind of summer-like weather in November is pretty rare even here though. Better go out and make use of it while we can. Of course, right now "go out and make use of it" for me mainly means reading papers in a café rather than at home, but at least it's something.

Mabo Ramen

With my recent post about ramen and curry and all, I wanted to mention yesterday's set meal at our university cafeteria: Mabo Ramen. "Mabo" is mabo tofu, a Chinese dish that resembles chilli: a fairly thin, spicy meat sauce with pieces of tofu. It's eaten with rice and is quite popular here. "Mabo Ramen", then, is a bowl of soy-sauce flavoured ramen, but instead of bean sprouts and the rest, you pour a ladle-full of mabo tofu right into the bowl and stir.

Soy-sauce ramen is fairly dark, and the meat sauce thickens it to resemble hot, dark mud. The white pieces of tofu float merrily on top, not unlike winter-pale, overweight guests at a spa enjoying a mud bath. Suddenly the surface erupts as the bone-yellow ramen floats to the surface like some blind, mad Lovecraftian Elder God. Its multitudinous¹ tentacled strands glisten as they blindly grope and envelop the first unlucky tofu bather, to drag him under, shrieking in fear, towards the unknowlable insane horror at the center of the huge slithering mass...

..and once I stopped playing with my food I tried actually tasting it. As it turns out, It's really, really good. The flavours complement each other very well, and the meat sauce gives the soup a thick, satisfying consistency. And it shouldn't be too surprising; after all, a mabo tofu and small ramen is a fairly common set menu at cheap Chinese restaurants already. Pouring them into the same bowl is just a natural next step. Anyway, I'm certainly having it again if it shows up on the menu at some point.

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#1 I really think "multitudinous" is a good word, and used far too little these days. It's not that easy to fit expressions like "multitudinous tentacles" into everyday conversation², unfortunately. "Multitudinous whiteboard markers" just doesn't have the same ring to it.

#2 If you can, you're probably leading a more interesting life than I do.

Autumn

It's finally autumn here. The leaves are starting to turn and daytime temperatures have dropped to 20° or so. The weather alternates between high, dry, brilliantly blue skies and leaden clouds with drizzling rain. The light is just a little subdued, the colors slightly muted. The evenings are cool and crisp, and the chill now lingers in the shadows even on sunny days. And all along comes the smell of damp earth and gently decomposing leaves. This is my favourite season.

We took a walk around Osaka castle last weekend to enjoy the end of summer. Turns out we were not the only ones with that idea; the castle park was teeming with people. Really, this is the best time of year to enjoy this part of Japan.

This quartet was having an English-style picknick in the castle park. Apparently they don't believe in doing things halfway.

Part of the outer moat - really a tributary of Neyagawa river - surrounding the park, looking northeast where a cluster of business high-rises adds some big-city ambience. Panasonic has a neat four-story interior and home-improvement exhibition here; you can while away an hour or so browsing kitchens, bathrooms, flooring and light fixtures.

There's several tree-lined roads like this one circling the park and they're very popular among walkers, runners and cyclists alike. These are Ginkgo trees; the leaves will turn a bright, clear yellow in another week or three.

They shed small, round nuts that are pretty good dried and roasted, but they're like ball bearings on the road and a danger to anybody with bad balance or weak legs. I head that the city only plants male Ginkgo trees nowadays, since they don't shed seeds.

The outer northwestern castle ramparts and a guard building. The castle area may not look like much for European eyes accustomed to wading hip-deep in medieval architecture, but it's still a very pleasant park in the city center. Also, it's gratifying to see that not everything in this city is torn down and destroyed once it becomes old and worn.

Saxophone player practising along the northern moat (he's in the big moat picture above too, along with another musician playing the banjo). I love the jazz-inspired clothing.

Homes and apartments don't have a lot of heat insulation due to the mild climate, but that means they're not very soundproof either - thick rock-wool insulation and triple glazing stops sound as well as heat after all. Amateur musicians playing brass winds and other loud instruments are often unable to practice at home. So you frequently find people like this gentleman practising in public parks, along rivers, under motorways or wherever they can without disturbing anyone.