There's a discussion on reddit at the moment concerning cycling, where one of the interesting assertions of recent research is that
overall public health would benefit from
no helmet laws and
more bike lanes.
That is: adults are less likely to ride bikes if they're required to wear a helmet (as I understand, laws for minors would remain), but the health benefits of increased activity and cycling outweigh the risks of injury.
open http://www.reddit.com/r/environment/comments/2ec8v5/forget_b...
I'm open to arguments over flawed methodology or other issues, but the point is that sometimes there are apparent safety measures that, when taken, increase risks. Another case in point would be TSA airport security measures, which by encouraging more trips to be made by automobile, have arguably increased overall death risks to travelers (as reported by Bruce Schneier and others). I'm among those who've either foregone or elected to drive on journeys rather than fly, even aware of the risks (and, frankly, if you've got the time, it's often far more interesting and enjoyable).
The US Department of Justice reports 685 successful recoveries, though it doesn't list the number of activations of the Amber Alert system, nor whether or not the recoveries were materially aided by the system.
http://www.amberalert.gov/statistics.htm
Edit: A more complete set of statistics and resolutions from 2002-2011 is given here, including ativation requests received but not resulting in alerts: http://www.statisticbrain.com/amber-alert-statistics/
According to that, there had been 190 activations (fewer than I'd thought), 77 were parental abductions (about 35%), acquaintances 55, strangers, 37. Another 355 alert requests were made but not activated.
The Wikipedia article on the Amber Alert system raises a number of the points I've mentioned above:
"A Scripps Howard study of the 233 AMBER Alerts issued in the United States in 2004 found that most issued alerts did not meet the Department of Justice's criteria. Fully 50% (117 alerts) were categorized by the National Center for Missing & Exploited Children as being "family abductions", very often a parent involved in a custody dispute. There were 48 alerts for children who had not been abducted at all, but were lost, ran away, involved in family misunderstandings (for example, two instances where the child was with grandparents), or as the result of hoaxes. Another 23 alerts were issued in cases where police did not know the name of the allegedly abducted child, often as the result of misunderstandings by witnesses who reported an abduction."
On stranger abductions:
"Seventy of the 233 AMBER Alerts issued in 2004 (30%) were actually children taken by strangers or who were unlawfully travelling with adults other than their legal guardians."
Regarding effectiveness:
"Some outside scholars examining the system in depth disagree with the "official" results.[60][61][62] A team led by University of Nevada criminologist Timothy Griffin looked at hundreds of abduction cases between 2003 and 2006 and found that AMBER Alerts actually played little apparent role in the eventual return of abducted children. Furthermore, AMBER Alerts tended to be 'successful' in relatively mundane abductions, such as when the child was taken by a noncustodial parent or other family member. There was little evidence that AMBER Alerts routinely 'saved lives'"
There are further concerns with AA as "crime prevention theater" (much as the TSA is seen as homeland security theater), of the "crying wolf" effect, over 4 a.m. cell-phone alerts, over use where the Alert criteria aren't met, of distraction effects of highway signage especially during rush hour, and more.
Contrasting AA with a widespread and imminent natural disaster or civil emergency alert:
In the case of an Amber Alert, a very small number of individuals are likely to be in a position to assist at all, let alone actually assist, in a recovery. Risking "alert fatigue" should be a very real concern. I am not opposed to forms of widespread message propagation, but these should be done through nonemergency channels (e.g., a news or other scheduled statement or alert), rather than by distracting drivers, waking sleeping people, or interrupting people engaged in other activities, the vast majority of whom have no bearing on the outcome of the incident.
In the case of an earthquake, tornado warning, tsunami alert, flash flood, landslide, wildfire, or similar event, people over a widespread area have seconds or minutes to act and take measures which will directly and materially benefit them by saving lives, preventing or reducing injury, and reducing harm or damage to property.
These are totally different situations.