Monday, January 27, 2014

Wilderness Trails Are Disappearing in California

Story from a life-long trail volunteer of funding cuts to wilderness preservation, and ideas of whether wilderness equals no access for any human, or no motorized vehicles (my understanding.) Volunteers are great but ultimately you can't run a government agency with volunteers.

Saturday, January 25, 2014

Expected Utility, Expected Points

Cross-posted to Cognition and Evolution MDK10 Outside.

New analysis of football stats at, from an expected utility standpoint, rather than just "yards gained". One yard from the 50 to the 49 yard line is not the same as one yard from 1 to the end zone. The article points out that even points expected is limited and must be considered when time is not a factor, since a team up by a single point will sacrifice the opportunity for more points just to run time off the clock, and avoid the small chance of turnovers. Of course the departures from rational optimization are the most interesting, but they don't get into that (yet). A lot of those apparent deviations from rationality may in fact be maximizing something besides win-loss records. Professional football is a commercial endeavor and isn't played in a vacuum, and contra Lombardi, winning isn't the only thing. Profit is.

Below: from the linked post. Note the (unsurprisingly) slightly sigmoidal (importantly: non-linear) shape of the curve, which is why expected points is not the same as yards gained.

Wednesday, January 22, 2014

Altitude and Population Density

Cross-posted to my history blog The Late Enlightenment.

We typically go to mountains to get away from it all, especially other humans. I'd always wanted to investigate the relationship between population density and elevation. Surprise! Such a relationship exists. The higher you go, the lower the density; in fact the relationship is even stronger than exponential. Even more interesting than that is understanding why. But first: figure below is from Cohen and Small 1998:

Note the bump at 2,300 m and again at 4,000+. 2,300 is mostly people on the Mexican Plateau, and 4,000 is Tibet + the Andes.

I plugged in data just for ~250 cities in the state of Utah, and got a worse R^2 than I saw for Cohen and Small's data (0.25 vs >0.9 for theirs), but this isnt' that granular; when I tried to do the same thing using mean elevations and population densities for the 50 states it was a mess. I think it would work a lot better at the county level.

So why is this? You might be tempted to speculate that it has to do with the limits of human physiology. That is to say, the higher you go, the more uncomfortable people are (thin air, cold) and the less adaptable, right? It's hard to imagine (for example) that Las Vegas at 665 meters would be a more comfortable place at a lower elevation. And physiologically, as it turns out, in the second half of the twentieth century medical anthropologists studied people in Tibet and the Andes extensively for their physiological adaptations to altitude - the underlying mutations for which have now been characterized (and in the Tibetan case have all occurred in the last 3,000 years!). But the idea that a few hundred meters of elevation will start impacting physiology and population growth falls apart both in terms of common sense and as a direct implication of other work. Any decrease in fertility caused by altitude would cut right at population growth - but this turns out not to be a big concern even for Himalayans living much higher.

You could also argue that the world's large cities tend to be seaports, which are at low elevation, so it's ease of transportation that gives us this bias toward lower elevations; but this is more true for New World that got settled by the sea than the Old World that got settled by land, and people must be pretty lazy if what's keeping them at sea level is their ancestors having gotten off a boat there a few centuries ago.

Terrace farming in the Himalayas.
I bet they would rather just have flat fields.

Beyond some historical accidents, the answer is likely to be mostly "agriculture". The overall population distribution we see in the world today basically reflects how early people in a certain part of the world adopted agriculture and how effective it was, given the crop and the climate, and escaped the Malthusian cycle; hence the highest densities being in a band running from east, southeast, and south Asia. The Middle East started early and although the marginal environment was also a driver for state formation, it was still marginal, and the Fertile Crescent just can't compete with the Ganges or the Pearl River. (So it can be accurately said that on average, humans are Asian; hence this map). So the relationship between elevation and population is really about where agriculture is better, and it's better at lower elevations for many reasons. Otherwise it's hard to understand the Mexican bump at 2300 meters, where (guess what) agriculture was first invented in the New World.

So, if someone ever thinks of a way to do agriculture as easily in the mountains as on flat lands, the days of undeveloped remote mountains are over.


Cohen JE and Small C. Hypsographic demography: The distribution of human population by altitude. Proc. Natl. Acad. Sci. USA, Vol. 95, pp. 14009–14014, November 1998.

Goldstein MC, Tsarong P, Beall CM. High Altitude Hypoxia, Culture, and Human Fecundity/Fertility: A Comparative Study. American Anthropologist 85(1), March 1983.

California is Bent: Geography Nerdiness for Californians

If San Diego shifted north to San Francisco’s latitude but kept the same longitude, it would be 273 miles inland, 70 miles deep into Nevada, between Henderson Park and the town of Alkali, near the NW edge of Groom Lake.

If San Francisco shifted south to San Diego's latitude but kept the same longitude, it would be 290 miles offshore.

The longest day of summer in San Francisco is 14 hours, 47 minutes, 28 minutes longer than in San Diego. In San Diego on that day, the sun still rises 6 minutes earlier (because SD is so much further east) but sets 34 minutes earlier.

The shortest day of winter in San Francisco is 9h33m, by symmetry, 28 minutes shorter than in San Diego. In San Diego on that day, the sun rises 34 minutes earlier and sets 6 minutes earlier.

On the East Coast, San Francisco is even with Richmond, Virginia. (And, believe it or not, with Cordoba Spain, and is a few miles north of Tunis.) San Diego is even with Charleston, SC, and farther east, it’s even with Morocco, specifically halfway between Casa Blanca and Marrakesh. This is why you can kind of compare the Mediterranean climate here with the "original" one in Europe. Partly because of the Gulf Stream (for which the eastern Pacific has no equivalent), the Old World climates are shifted north. (Glasgow is at the same latitude as the Alaska panhandle!) So weather-wise, San Francisco and San Diego are kind of like North America's Bilbao and Tangier.

Now go about your business.

Monday, January 20, 2014

Geographic Analysis of Superbowl Winners: No Temperature, Distance or Time Zone Effects

In sports, even in championship games that are supposedly on neutral ground, some teams are thought to have home advantage if they play in or near their home state, for whatever reason; cultural similarity, less wear and tear from traveling, etc.. Do we see this in Superbowls?[1] (I didn't find any effects here so you can scroll up for a little more interesting one on ratings if you want.)

Not really. The winners, on average, have actually had to go a little farther from home than the losers (winners are on average 1487 miles from home, losers 1409, using Google maps driving distance to approximate.) And the home-state advantage, so far as it's happened - only four times so far, all with California teams playing in Cali - is a wash (2 wins, 2 losses). I also checked to see if the curve is U shaped, inverted or otherwise. For instance, if it's inverted U, maybe it's rough to take a 400 mile bus ride since further than that, you fly, and a full transcontinental flight is dehydrating and stiffening. But no dice. (If I cared, I would look at overall NFL records, not just the Superbowl, unless we're assuming the Superbowl is different.)

Above: distribution of Superbowl Games I through XLVII

Above: Superbowl wins and losses (#wins and losses proportional to radius of circle)

Seeing the maps above, you can tell that Superbowls and Superbowl teams are not distributed randomly. There's an obvious bias to the Northeast, as would be expected based on population density (and bigger markets). These maps show wins by CITY, not franchise (unless the franchises have remained stable and separate - so Jets and Giants are separate, but L.A. Raiders and Rams are not). But all things being equal, this should come out in the wash anyway.

So what about time zone changes? There's a known effect in sports called circadian advantage; it's assumed in medicine that we can adjust our circadian rates up or down 5%, so that we can adjust to one hour of time difference for each day. In fact in a peer-reviewed 1997 paper on Monday night football game advantage in the NFL, it was shown that West Coast teams do significantly better over East Coast teams than Vegas odds predict. (Note this is for night games, as would be expected.) It turns out that there is a slight but not significant difference overall: counting the Eastern time zone as 1, Central as 2, Mountain as 3 and Pacific as 4, Superbowl winners are from a little bit further east, with an average time zone of 1.8 vs the losers' average time zone of 1.9. There was no association between score margin and time zone either. I also checked to see whether there was any advantage to being closer to the time zone of the Superbowl location, or being from an earlier or later time zone, but there was not (the distribution was just about exactly coin-toss random).

While we're worrying about environmental factors, we might as well look at temperature - the home field's December average temperature, against the temperature on the field at the Superbowl. There is no clear curve for any relationship I checked (team's home December average temperature vs points scored, or difference from Superbowl city average temperature vs points scored.) There is a slight difference in terms of average "distance" (could be warmer or colder) between a team's home city, and the Superbowl city: winning teams are 20.9 degrees Fahrenheit off from the Superbowl temperature, and losers are 23.4 degrees off. In non-absolute value terms, the winners are on average 19.2 degrees colder at home vs the Superbowl, and the losers are 21.2 degrees colder at home.

What does this tell you about the Seahawks-Broncos matchup? Nothing! Who cares!

[1] Yeah, I said Superbowl. Not "big game". S-U-P-E-R-B-O-W-L, as in NFL. Listening to commercials you'd think saying Superbowl summons He Who Cannot Be Named or something.

[2] Smith RS, Guilleminault C, Efron B. Circadian rhythms and enhanced athletic performance in the National Football League. Sleep. 1997 May;20(5):362-5.

Sunday, January 19, 2014

Add Your Own Close Calls: The Rattlesnake Encounter Map

View Rattlesnake Encounters in San Diego County in a larger map

Clicking on that nasty-looking reptile you see to the right will take you to the map you see above, which is a public-access Google map for people to mark rattlesnake encounters in San Diego County. My purpose in putting this together was to get an idea if there were certain spots where people routinely encountered snakes outdoors. It's been up for a little over a year and a half and as of today there are 15 encounters on it; so far it hasn't been enough to show if there are any hotspots. But either way, I appreciate the contributors!

I'm going to leave it up (and linked on this blog) but probably won't plug it again. So, if you see one of these critters out there, or someone mentions to you that they have, you can tell them to do a Google search for "rattlesnake encounter map" and they'll find it. Hey, if it helps one less person get bitten by a snake, it's worthwhile.

California Drought State of Emergency is Here

Added later: Dave Stillman posts the really terrible precip stats for Santa Barbara and southern Los Padres. We're in trouble here people.

Right now conservation is voluntary but I bet Brown wouldn't mention it unless full rationing is coming. Until then: save the "warming-up" shower water in buckets for lawns and plants, and if it's yellow let it mellow. (Our drought now is considerably worse than the one which brought about that policy.)

There's a fire burning above Azusa right in Angeles NF and the 3 men who started it are in jail. I'm glad we're starting not to tolerate life-, property-, and forest-endangering nonsense.

Saturday, January 18, 2014

Del Mar Mesa Trail Work: Saturday 25 January 2014

This is being run by Friends of Del Mar Mesa - if you're interested and want to contact them, check them out on Facebook.

Where: Park & meet on Aquitaine Court off DMM Road (see map on next page)

When: Saturday, January 25th, 8:00 – 11:00am

What you'll be doing: Trail clearing/restoration (east & west ends of "Angel" trail) & trail sign installation

What to bring: Tools (e.g., shovels, rakes, McLeods, loppers, etc.)

What they'll bring for you: Gas hedge trimmer, trail signs on posts (2), post-hole digger

What to wear: Work clothes, boots, gloves, hat, sunscreen, sunglasses

Wednesday, January 15, 2014

Another (Separate) Delay at Del Mar Mesa

City officials have dragged their feet on a small community park adjoining the area. (Please check out that link, which also has lots of links to previous Del Mar Times articles on this topic.) This is a different issue than the planning of Del Mar Mesa Preserve, which has been going on for a while. It's a fantastic area of open space south of the 56 that is currently closed to trail users, who have been fined and even had bikes confiscated. This should all be open by now. The city and state are screwing up. And people want this smaller park as a jumping off point. The locals are most incensed by the delay because they recognize that adjacent open space increases property values.

So it's either a) the city and state government just suck at everything, or b) there's something specific going on with Del Mar Mesa.

I hope it's just incompetence. But my suspicion has been that there are property developers who want things delayed, and they're exerting influence this way. Every separate event that occurs raises suspicion further. That's why I'm trying to help make this as public as possible, for the trail users and outdoors folks of San Diego.

In the meantime, they need volunteers! Friends of Del Mar Mesa treasurer Preston Drake will hold a trail clearing project Jan. 25 and needs volunteers to help clear Angel trail. Volunteers will be asked to pick up debris, cut pampas grass, and trim hedges. More information here.

Look at all those trails! All off-limits right now, thanks to whatever's going on.

Oh Our Warm Weather Is So Great, We Say As We Die of Thirst

If I see one more person on Facebook bragging to their relatives back East about our great weather...

Red means extreme, orange means severe. San Diego is in severe drought. (Relative to our usual sparse desert-like rainfall.)

Quick quiz. What was California's driest year ever in history? Give up? 2013. RIGHT NOW. Wells have already dried up. We have pretty bad fire danger. In January.

It's January. It should be raining. And this drought is most painfully obvious when you go over to the now-almost-non-existent Lake Hodges. And it is about to become more painful because municipalities will have no choice but to impose rationing, which will make people cry like a first-grader, but the alternative is you get in the shower and air comes out. The governor is about to announce a drought. If you're still doubting, here's how we stack up to the rest of the country.

Tuesday, January 7, 2014

The Boston Marathon...Not That Long Ago

In 1972 (1972!) women weren't allowed to run Boston. Actually it wasn't until 1977 that they were allowed to run, largely as a result of what Kathrine Switzer did in 1972. What's amazing is that based on the story, and based on the footage, the participants in the race seemed completely supportive. Oddly, it was the race director who had the problem.