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Rules - Qualified Perceptions
So, we got one of the $100 "obstructing snow plow" tickets for parking over at twinknj last night. When, of course, there was no snow. (My fault, I knew there was a snow emergency at 4; I had gotten confused and thought it was 4am, when there would actually be snow). Bah.

The trouble is, Somerville has a declared policy of "ticket and/or tow way before there's snow" (including two years ago when they ticketed 3000 cars and towed 150 when it snowed an inch). By being particularly draconian about this, they can, in fact, keep cars out of the way of plows when there *is* snow. And I can't argue with that, because it works.

But it's yet another example of the Way Things Work that bugs me. In order to get reasonable behavior, we have to outlaw not only unreasonable behavior but a whole area around the edge, because otherwise you can't be sure you get the edge cases. If the speed limit is 60 MPH, then the prevailing flow of traffic goes 70[*]. Schools write harassment policies that end up suspending 6-year-olds for sexual harassment when they grab another 6-year-old by the waistband, so they can be sure that they're on firm ground for things that actually resemble harassment as most of us know it. "Traffic calming" solutions, like those raised intersection areas, slow me down to about 15mph, when I have to assume that what they really care about is that people not drive 50 through the neighborhood.

Essentially, they're systems which are skewed towards allowing a lot of false positives, rather than running the risk of allowing false negatives. I used to think that in an ideal world, we could make the rules actually between right and wrong, but now I wonder if it just always has to be a choice between which failure case you care more about.

*: I make the assumption here that the (possibly evolved) desire is to stop people from going 80, rather than really stop them from going 60. If it's the latter, they're just failing utterly.

Current Mood: snowy
Current Music: City of Angels

11 comments or Leave a comment
dpolicar From: dpolicar Date: February 12th, 2006 04:20 pm (UTC) (Link)
Well, yes, it's always a choice between which failure you care more about. But there's more dimensions than false positive/negative.

You can bring the threshold of error down arbitrarily low - reducing false positives and false negatives both - but to do so you need to spend a lot more resources. And those are resources you can't then spend somewhere else.

With infinite resources in an ideal world we could be arbitrarily accurate about how we enforce our rules. Of course, by the same token we'd have far less need to do so... infinite resources can support quite a lot of unreasonable behavior.
firstfrost From: firstfrost Date: February 12th, 2006 04:32 pm (UTC) (Link)
True. Though it's not always a question of error of judgement, as of "how much do you care about the effect" being a spread over various people rather than a single amount. There are probably people who are willing to drive faster than me over speed bumps, no doubt in part due to different car suspension and undercarriage height, so even a perfectly designed speed bump won't exactly separate people at the right speed. I suppose one could introduce a different sort of slowing measure, like automated radar guns and cameras at all the intersections...

(I'll note that when I think about "my ideal world," I think about one in which people are all pretty much good-intentioned, and clever and far-sighted enough to set things up right; I don't also posit infinite resources.)
dpolicar From: dpolicar Date: February 12th, 2006 06:40 pm (UTC) (Link)
If everyone is good-intentioned, clever, and farsighted, you don't really need to enforce a speed limit. You can do the research about the various consequences of driving at various speeds, statistically speaking, and publish it, and let people drive at whatever speed they like, knowing that whatever happens they will more or less deal with the consequences in a reasonable way.
mjperson From: mjperson Date: February 12th, 2006 05:17 pm (UTC) (Link)


I'm very sorry you got ticketed for bumming around at our place last night.
mijven From: mijven Date: February 12th, 2006 11:04 pm (UTC) (Link)

Re: Doh!

(And I'm sorry she got a ticket for driving under the speed limit near ours. Eek.)
firstfrost From: firstfrost Date: February 13th, 2006 01:08 am (UTC) (Link)

Re: Doh!

Actually, for the ticket near your place, we were driving *over* the speed limit, just not enough over. The policeman criticized us for only going 70. :)
From: readsalot Date: February 13th, 2006 04:30 pm (UTC) (Link)

Re: Doh!

When I was a kid, the speed limit on highways was generally 70, so everyone went at least 90.
zubatac From: zubatac Date: February 12th, 2006 08:51 pm (UTC) (Link)
Somerville's recent approach to parking enforcement (and snow parking in particular) really makes me wonder whether the goal is to increase revenues for the city as well as encourage reasonable behavior among the populace... Funny how there's a certain synergy there.

Not that this is so different from your speed-limit example. >=)
firstfrost From: firstfrost Date: February 13th, 2006 01:14 am (UTC) (Link)
For the Dec. 10 snowstorm, they lifted the snow emergency at midnight, thus requiring anyone who had parked in one of the emergency lots to remove their car by 2am or be subject to ticketing/towing. Now, *that* just sounded like an increase in revenue, as opposed to any pretense at encouraging reasonable behavior.
twe From: twe Date: February 13th, 2006 12:19 am (UTC) (Link)


$100 is a big ticket, but I suppose it's better than being towed.
kirisutogomen From: kirisutogomen Date: February 15th, 2006 02:06 pm (UTC) (Link)
I understand skewing your regulations to suppress false negatives at the expense of allowing false positives. It makes sense. Speed bumps, "traffic calming," etc., are fine by me.

What bugs me the most, though, is lack of clarity. If everyone knows at any given moment whether they're breaking the rules as enforced, any given incentive structure works better. What irks me is that setting the speed limit at 60 mph but only ticketing people for going some unknown amount over that leads to uncertainty about whether you're actually breaking the rules or not.

Now, if the probability of getting caught when breaking the rules were very high, this uncertainty would lead to extra caution, which would be the point of the skewed system. But the probability of getting caught for speeding or parking wrong is also fairly low, so the uncertainty is compounded to where it's easier to just model parking tickets or speeding tickets as completely random events that don't depend on my behavior at all.

(The sexual harassment thing seems like a different issue. I feel like you could write an overly conservative policy that didn't result in complete absurdities like banning hugging or suspending six year olds.)
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