MetaSD – Page 62 – Don't just do something, stand there! Reflections on the counterintuitive behavior of complex systems, seen through the eyes of System Dynamics, Systems Thinking and simulation.

Superstitious learning about the stimulus

Stimulus regret seems to be pretty widespread now. The undercurrent seems to be that, because unemployment is still 10% etc., the stimulus didn’t work or at least wasn’t cost effective. This conclusion is based on pattern matching thinking. Pattern matching assumes simple A->B correlation: Stimulus->Unemployment. Working backwards from that assumption, one concludes from ongoing high unemployment and the fact that stimulus did occur that the correlation between stimulus and unemployment is low.

There are two problems with this logic. First, there are many confounding factors in the A->B relationship that could be responsible for ongoing problems. Second, there’s feedback between A and B, which also means that there are (possibly large) intervening stocks (integrations, accumulations). Stocks decouple the temporal relationship between A and B, so that pattern matching doesn’t work .

Consider three possible worlds, schematically below. The blue scenario is the economy’s trajectory with no intervention. In the green scenario, stimulus spending is used, and it works, making recovery faster. In the red scenario, stimulus is counterproductive. If one evaluates the stimulus early, without accounting for delays and accumulation, one can’t help but conclude that the stimulus has failed, because things got worse. Pattern matching doesn’t account for the fact that things might have gotten worse more slowly.

For a politician evaluated by people who ignore system structure, this is a no-win situation. As long as things get worse, blame follows, regardless of what policy is chosen.

I’m not arguing that stimulus works, just that the public debate about it is vacuous. There’s little talk about delays, feedback, let alone model-driven discussion of the outcome, i.e. the only perspective through which one can understand the problem is largely confined to a small circle of wonks.

Interactive diagrams – obesity dynamics

Food-nutrition-health-exercise-energy interactions are an amazing nest of positive feedbacks, with many win-win opportunities, but more on that another time.

Instead, I’m hoisting an interesting influence diagram about obesity from the comments. At first glance, it’s just another plate of spaghetti.

But when you follow the link (do it now), there’s an interesting innovation: the diagram is interactive. You can zoom, scroll, and highlight particular sectors and dynamics. There’s some narrative here and here. (Update: the interactive link seems to be down, but the diagram is still here: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/295153/07-1177-obesity-system-atlas.pdf)

It took me a while to decide whether I’d call this a causal loop diagram or not. I think the primary distinction between a CLD and other kinds of mindmaps or process diagrams is the use of variables. On a CLD, each label represents a quantity that can vary, with a definite direction – TV Watching, Stress, Use of Medicines. Items on other kinds of diagrams might represent events or fuzzier constellations of concepts. This diagram doesn’t have link polarities (too bad) or loop polarities (which would be pretty incomprehensible anyway), but many other CLDs also avoid such labels for simplicity.

I think there’s a lot of potential for further exploration of this idea. There’s a lot you could do to relate structure to behavior, or at least to explain the rationale for structure (both shortcomings of the diagram). Each link, for example, could have its tale revealed when clicked, and key loops could be animated individually, with stories told. Drill-down could be extended to provide links between top-level subsystem relationships and more microscopic views.

I think huge diagrams like the one above are always going to be overwhelming to a layperson. Also, it’s hard to make even a small CLD good, so making a big one really accurate is tough. Therefore, I’d rather see advanced CLD presentations used to improve the communication of simpler stories, with a few loops. However, big or small, there might be many common technological benefits from dedicated diagramming software.

Dry Lake Mead

The systems story on Lake Mead deepens (unlike the lake itself). I heard about some more interesting dynamics in a side conversation at the Balaton Group meeting in Iceland.

First, it’s not just Mead that’s impacted; upstream Lake Powell is also low. One consequence of this is that hydro generation is down, because the head is lower. Since both lakes are half full, it might make sense to drain Powell into Mead. That would raise the head at Mead, making up for the loss of generation at Powell. Water losses would also decrease. One possible obstacle to this strategy is that stakeholders in Powell fear that it could never be refilled, because endangered species would reinhabit the empty canyons.

Second, as the lakes get lower, bad things happen. Evidently the deep waters are stratified, and there are plumes of nasty saline gunk near the bottom. If lake levels continue to drop, there’s a possibility of serious water quality problems to go with the quantity issues.

One thing that’s striking about the media coverage of data and projections by agencies is that there’s little discussion of the nature or magnitude of variability. The implicit assumption behind current behavior is that droughts are cyclical or just noise. The hope seems to be that, since we’re in a low period for basin rainfall, the magic of reversion to the mean will soon bring forth the waters again. I don’t think there’s any good reason to act as if that will really happen, especially if climate makes the distribution nonstationary. Modelers seem to think that the Southwest will move to a drought regime as the earth warms, but what if they’re wrong, and the hydrologic cycle accelerates? Glen Canyon Dam was nearly lost in 1983, so a healthy increase in rainfall wouldn’t necessarily be a blessing either.

Current Bureau of Reclamation projections for Lake Mead elevation. Documentation is pretty opaque, but it looks like the projections are based on quantiles of historic inflows, i.e. they neglect autocorrelation or changes in the distribution of supply.

Edward Abbey must be smiling at least a little at this mess.

Why is the arctic brown?

I’m blogging from a 757, somewhere over the North pole, returning from a sustainability meeting in Iceland. The world below is a wilderness of sea ice and clouds. I’d expect brilliant white, but there’s actually a brown haze over the landscape. It’s stratified, much like the odd sight of half-white, half-brown clouds one occasionally sees when flying into a polluted city. Where does it come from? Chinese coal fumes? Russian fires? American SUV tailpipes? Icelandic airplane exhaust?

You are what you eat

I’m on my way home from the 29th meeting of the Balaton Group, held in Iceland. Iceland seems to be rising gracefully from it’s financial crisis, with introspection into the values that led to it and a renewed interest in sustainability. Author Andri Magnason visited us at dinner, and talked a bit about Iceland and his wonderful book, Dreamland – A Self-help Manual for a Frightened Nation. I picked up a copy in the airport (can’t get it at amazon yet) and got halfway through on the plane – I highly recommend it.

Another Magnason project is a book of Bonus Poetry, named for and spoofing the Icelandic Walmart.

You are what you eat
My grandfather was 70% water
He was 70% the stream
that trickled past his farm
he was the 30%
the sheep that grazed on his mountain
he was the fish swimming in his lake
he was the cow eating
in his field
he was the stream, he was the grass,
the mountain and the lake
I am not 70% water
perhaps 15% mineral water
the rest is beer and coca cola
I am italian pasta, swiss cheese
danish pork and chinese rice
american ketchup
runs through my veins
you are what you eat
I am a miniature of the world
no
I am a miniature of Bonus

Fuel economy makeover

The EPA is working on new fuel economy window stickers for cars (you can vote on alternatives). I like this one:

hoisted from the comments at jalopnik

There are some things to like about the possible new version. For example, it indicates fuel economy on an absolute scale, so that there’s no implicit allocation of pollution rights to bigger vehicles (unlike Energy Star and the CAFE standard):

Since the new stickers will indicate fueling costs, emissions taxes on fuels will be a nice complementary policy, as they’ll be more evident on the dealer lot.

Causal loop diagram smorgasbord

The new layout of google image searches makes quite a nice visual when you point it at causal loop diagram:
Click through for the really big version.

While I’m at it, here’s an interesting link on the structure of earth system models.

A spiny treat

No time to write anything lately, so here’s a pic of an elk thistle, in a rocky chute at almost 10,000 feet in Beehive Basin, near Big Sky, MT. In 1870, Truman Everts was lost in Yellowstone for 37 days, and survived largely by eating these.

Waiting for a miracle at Lake Mead

Lake Mead has dropped another ten feet since I wrote about its open-loop management,

My hypothesis is that the de facto policy for managing water levels is to wait for good years to restore the excess withdrawals of bad years, and that demand management measures in the interim are toothless. That worked back when river flows were not fully subscribed. The trouble is, supply isn’t stationary, and there’s no reason to assume that it will return to levels that prevailed in the early years of river compacts. At the same time, demand isn’t stationary either, as population growth in the west drives it up. To avoid Lake Mead drying up, the system is going to have to get a spine, i.e. there’s going to have to be some feedback between water availability and demand.

An article in the Arizona Republic confirms my thinking,

To slow the lake’s years-long decline, river users have built a reservoir west of Yuma to catch unused runoff, paid farmers to leave fields unplanted and are negotiating with Mexico to leave some of its allocation in Lake Mead while its farmers recover from an earthquake.

None of the steps will yield significant amounts of water, but together, they could keep Lake Mead from sinking below the drought triggers, buying time until a wet winter can replenish some of the water lost to drought.

“It’s time that we need,” said David Modeer, general manager of the Central Arizona Project, which moves water from the Colorado River to Phoenix and Tucson. “The reservoirs have shown they’re resilient. After a 12-year drought, they’re still half-full. What we do now will be worth it to stay out of a shortage.”

Managers are assuming that a return to historic rainfall patterns will save their bacon. But if climate models are right, and the Southwest will be on the losing end of trends in precipitation, that won’t happen. Even if they’re wrong, increasing demand can easily overwhelm restored rainfall. At some point, the loop will have to close – the question is how. Will property rights get reallocated and price signals aligned so that people live within the limits of supply? Or will the lake wind up permanently depleted? There are some signs of improved cooperation among states, but Nevada appears to be betting on failure:

if the reservoir fell below elevation 1,050 feet, one of the tunnels Nevada uses to draw water from the lake would sit above the waterline and would be useless. Nevada is working on a new, deeper tunnel

Gallatin County's Zoning Enforcement Trap

I’m playing a big role in a local effort to get the regulations of our zoning district enforced in the case of an egregious violation. Our planning and zoning commission’s habit, and apparent preference in this case, is not to enforce. Instead, it is proposed to enable the violation through a PUD amendment, and issue a trivial fine ($200, or 0.2% of the stated value of the structure).

Unfortunately, this proposal is illegal, because it contradicts existing covenants and a variety of goals and specific provisions of our General Plan and Zoning Regulation. This action might make sense if it were a naked political ploy to undermine the zoning through administrative rather than legislative means, which I hope is not the case. I think it is more likely an effort to “play nice” with violators and to avoid costly enforcement action.

If so, the resulting weak enforcement posture is a short-sighted avoidance of conflict, that encourages far more problems in the long run. As the diagram below illustrates, backing down on the case at hand solves the immediate problem, but has terrible consequences.

The precedent for non-enforcement and amendments to legalize violations erodes the legal basis for future enforcement actions.
Accommodation creates an expectation of forgiveness, encouraging owners and builders to violate in the future.
Exceptions created to accommodate violations make planning documents and title histories more complex, creating more opportunities for errors.

These side effects of lax enforcement accumulate. As violations mount, time that could be spent on productive activity (ensuring a thorough permitting process, or revising zoning regulations to clarify standards and streamline processes) gets squeezed out by time wasted on enforcement.

These reinforcing feedbacks create a deadly trap, into which the unsuspecting can easily step. Once triggered, the vicious cycle creates more pressure to relax enforcement standards, capturing the county in an undesirable equilibrium with many violations and no meaningful enforcement. Ultimately, the citizens (who initiated the zoning district) suffer from the side effects of density granted to violators, that is unavailable to those who comply with the law.

Fortunately, with a little fortitude, the process can be reversed. A single forceful enforcement action has a salutary effect on expectations, stemming the tide of violations and freeing up time for the improvement of regulations. There’s still the hangover of side effects of past accommodation to contend with, but surely the withdrawal is better than the addiction to accommodation.