May

Although it's often thought impossible to predict, that is with certainty, the behavior of a complex network, we may be getting closer to it. "Controllability of Networks"—a recent article in Nature (May 12, 2011) by Yang-Yu Liu, Jean-Jacques Slotine, and Albert-Lázló Barabási—shows that it is possible to control the behavior of a complex network. From the abstract:

The ultimate proof of our understanding of natural or technological systems is reflected in our ability to control them. Although control theory offers mathematical tools for steering engineered and natural systems towards a desired state, a framework to control complex self-organized systems is lacking. Here we develop analytical tools to study the controllability of an arbitrary complex directed network, identifying the set of driver nodes with time-dependent control that can guide the system’s entire dynamics. We apply these tools to several real networks, finding that the number of driver nodes is determined mainly by the network’s degree distribution. We show that sparse inhomogeneous networks, which emerge in many real complex systems, are the most difficult to control, but that dense and homogeneous networks can be controlled using a few driver nodes. Counterintuitively, we find that in both model and real systems the driver nodes tend to avoid the high-degree nodes.

The MIT News Office has a press release giving a few more details. Basically, complex networks can be analyzed to show the critical "driver nodes", which can be used to control the system, whether biological, social, or electronic. The fewer the driver nodes, the easier it is to control, and vice versa.

What's surprising is that hubs aren't necessarily drivers. In a social network, for instance, the person with the most friends may not be the one with the most influence.



Liz Robbins (New York Times) reports on the problems involved in the New York City's school choice maze:

The Department of Education’s dizzying, byzantine system for students to select a public high school left a total of 8,239 — about 10 percent of the city’s eighth graders — shut out of all their choices, and their parents feeling inadequate, frustrated and angry.

They were told to ponder “What next?” — with just two weeks to research and apply to a new set of schools — even as the bitter question “Why?” still lingered.

The answer is more complicated than the toughest word problem in any high school math class.

A major part of the problem was that the information needed to make a choice is simply not available to parents. However, the information available does correlate to socioeconomic class:

Information drives any choice system in the marketplace, said Henry M. Levin, a professor of economics and education at Teachers College, Columbia University. In the high school admissions process, information really is power.

“The upper-middle-class families have more of it; they can look at mavens who have gone through the process and can tell others how to game the system,” Dr. Levin said.

Another problem is that competition does not make all schools better as evidenced by the New York City system. Boudreaux concluded in his article:

In reality, of course, groceries and many other staples of daily life are distributed with extraordinary effectiveness by competitive markets responding to consumer choice.

However, distribution does not guarantee quality. And as long as parents are un-informed, schools that are less than competitive do not have sufficient stimulus to improve.



Donald J Boudreaux on The Wall Street Journal has a provocative article, If Supermarkets Were Like Public Schools. He begins:

Teachers unions and their political allies argue that market forces can't supply quality education. According to them, only our existing system—politicized and monopolistic—will do the trick. Yet Americans would find that approach ludicrous if applied to other vital goods or services.

And then he does a step-by-step illustration of running supermarkets like public schools. And he ends with:

In reality, of course, groceries and many other staples of daily life are distributed with extraordinary effectiveness by competitive markets responding to consumer choice. The same could be true of education—the unions' self-serving protestations notwithstanding.

Although his illustration is well worth considering, where it falls down is the ability of consumers to evaluate goods. With respect to food, I buy according to cost and taste value. Cost is in plain sight, and I conduct my own taste experiements on different brands. There is no spin factor involved. However, what would be the evaluation criteria by which to evaluate education? If cost, does that mean that families with less income would choose to less-cost schools? That might be okay for food, but would it work well for education? What equivalent to taste is there for schools? I suppose test scores could be used, but would poor-performing private schools release test score results? And although I know quite definitely what I like with respect to taste, understanding test scores and other metrics is not as straightforward.

In fact, test scores are not the only factors influencing parental choice. For example, Lynn Bosetti (see references below) surveyed parents from 29 elementary schools in Alberta and found a variety of factors, such as Academic Reputation or Excellence, The Teachers, The Principal, Teaching Style, Good Work Habits, Self-Discipline, Critical Thinking Skills, Building Self-Esteem, Shared Values and Beliefs, Smaller Class Size, Special Programmes, Proximity to Home, and so on.

Obviously, such a variety and number of factors is more complicated than the two of cost and taste—three factors if you add in customer service. I'm not against parental choice, but the comparison between schools and supermarkets doesn't do justice to the difference in the complexity of choosing a supermarket and that of a school.

Perhaps more important than the number of factors is the lack of information for parents to make choices. According to Buckley and Schneider,

Despite the argument that if given choice parents will become more informed about the schools, critics of choice argue that education is a complex good, that it is difficult to describe in a way people understand, and that less educated parents (who can probably benefit most from any system of expanded choice) are the least able to access and analyze information. Seizing on this disjuncture of theory and reality, critics argue that given the lack of good information among “parent/ consumers” the success of choice reforms is unlikely (see e.g., Ascher, Fruchter, & Berne, 1996; Bridge, 1978; Public Agenda, 1999).

The empirical evidence shows that, in fact, parents on average have little information about their schools, and even parents residing in districts with choice programs do not have the level of information that the demand-side arguments of choice proponents would predict (Public Agenda, 1999; Schneider et al., 2000).

Schools are more difficult to evaluate, and the information in evaluating them is more difficult to find. Yet, the consequences of misevaluating a school is considerably greater than those of misevaluating supermarkets. Although there's no question that education in the U.S. needs to be improved, it's unlikely that a supermarket choice approach will actually create the market conditions necessary for improving schools.

Reference:

Bosetti, Lynn (2005). Determinants of school choice: understanding how parents choose elementary schools in Alberta. Journal of Education Policy , 19, 387-405.

Buckley, Jack, and Mark Schneider (2003). Shopping for Schools: How Do Marginal Consumers Gather Information About Schools? Policy Studies Journal, 31, .



ScienceBlog reports on how media multitasking is really multi-distracting.

Placed in a room containing a television and a computer and given a half hour to use either device, people on average switched their eyes back and forth between TV and computer a staggering 120 times in 27.5 minutes — or nearly once every 14 seconds, Carroll School of Management professors S. Adam Brasel and James Gips report in a forthcoming edition of the journal Cyberpsychology, Behavior, and Social Networking.

...

What’s more, the subjects were not even aware of their own actions. On average, participants in the study thought they might have looked back and forth between the two devices about 15 times per half hour. In reality, they were looking nearly 10 times as often. And even if quick “glances” less than 1.5 seconds are removed from the equation, people were still switching over 70 times per half hour.

If simply being in an urban city can impair your memory and "dull your thinking", just imagine how much multitasking interferes with learning.