by Steven R. Corman

by James Joyner, outsidethebeltway.com

At last, the AP is reporting, someone is finally going to review our moronic “terror alert system” (TAS).

Homeland Security Secretary Janet Napolitano is expected to appoint a panel to reevaluate the system and determine whether it should be changed, or possibly eliminated.

Good for her.  The existing system, put in place shortly after the 9/11 attacks, have five levels of “threat” of terrorist attacks.  The AP story reports:

Currently, the alert level is at orange for the aviation sector, and yellow for the rest of the country. The nation has never been below yellow since 2001, although Hawaii put itself at blue for a year after the national system was adopted. It has since raised the level to yellow.

I believe the aviation sector has been at orange since the beginning, also.

The problem with the current system is that it runs afoul of something called the “information model of variance,”  developed by astronomers in the late 1800s and generalized by Shannon and Weaver in their 1949 Mathematical Theory of Communication.  The principle is simple:  Variability in a measure carries information about the thing being measured.  A correlary is that no variance in a measure means it carries no information.  Since the Terror Alert System never varies, it carries no information.  And because information conveys meaning, the system is– literally– meaningless.

Besides the fact that the TAS carries no information, there is an issue of what  people would do with the information, if it did carry any.   From the outset, it has never been clear how anyone was supposed to react if the alert went from one level to another.

Compare this to other common altert systems.  I live in Phoenix, where we occasionally have air polution alterts.   When we have a high particulate polution day, particular restrictions go into effect.  Leaf blowers can’t be used on commercial property.  People can’t burn wood in fireplaces or have open fires outside.  Use of off-road vehicles is banned.   Or take the place I used to live, central Illinois.  When we had a tornado warning, people were supposed to go to the basement.

So my humble advice to Secretary Napolitano comes in two parts.  First, if we are going to have an alert system that presumes to measure a level of risk, design it so the risk level does in fact vary.  This may just be a matter of making it more fine grained, so as to take into account “smaller” events and conditions that come and go.  Without variance, the system carries no information and has no communication value.

Second, make sure that the changes in level correspond to definite courses of action.  Like a pollution advisory system or tornado warning, when the level increases people should be expected to do things, and when it goes down they should be expected to stop doing them. Those who are expected to respond should know what the courses of action are, and they should be reminded when the changes occur.

The most ideal situation would be if the actions people take when the levels go up would have an impact on bringing the levels back down.   This creates a deviation-counteracting control system (the intent behind the pollution warning system), and would give the people using the alert a sense of efficacy.

If these two goals can’t be accomplished, then just scrap TAS.  Rely on ad hoc government advisories through the news media, etc., to inform people when there are terrorism problems and what they should do.