This is in keeping with what we know about neurophysiology. The frontal lobe of the brain starts to develop at around 16 years of age and is only fully developed by about age 23 (age 20 in girls). This is the area of the brain in which we assess risk, so it is hardly surprising that a 16-year-old boy makes reckless decisions. Medically speaking we should probably be extending the driving age to around 25, but this is not particularly practical.

Most parts of Australia now have graduated licenses that start at age 17 or 18. It should come as no surprise that Australia has about 60% of our youth fatality rate per kilometer driven. That is more that a third less teenagers slaughtered on our roads. New Jersey has had a graduated license system since 2001 offering a restricted license from age 17 for a minimum of a year (full license from 18 years). The fatal accident rate for 16-year-olds has halved and there have been substantial reductions in 17 and 18-year -old fatalities. Clearly the system works.

Interestingly, the increase in the driving age, somewhat immobilising 16 and 17-year-olds, has also been shown to reduced drug and alcohol use in these age groups, as an added side benefit. So when you hear 15-year-olds arguing that their freedom is being trampled on by raising the driving age, just remember that the freedom they are talking about is the one that entitles them to get slammed out of their minds on a Friday night and then wrap their car around a tree at high speed.

My idea of fun does not encompass digging bark out of the skull of a teenager in the early hours of Saturday morning.

Mr. Joyce should have ignored the ill-informed twitterings of Federated Farmers and raised the driving age immediately to 17. He will now have to engage in the same battle in a couple of years time, when it becomes crystal clear that this is what he should have done the first time.

Some journal references (sorry, only links to abstracts)

Voas, Robert and Kelley-Baker, Tara(2008) ‘Licensing Teenagers: Nontraffic Risks and Benefits in the Transition to Driving Status’, Traffic Injury Prevention, 9: 2, 89 — 97

McCartt, Anne T. , Mayhew, Daniel R. , Braitman, Keli A. , Ferguson, Susan A. andSimpson, Herbert M.(2009) ‘Effects of Age and Experience on Young Driver Crashes: Review of Recent Literature’, Traffic Injury Prevention, 10: 3, 209 — 219

Williams, Allan F. , Chaudhary, Neil K. , Tefft, Brian C. andTison, Julie(2010) ‘Evaluation of New Jersey’s Graduated Driver Licensing Program’, Traffic Injury Prevention, 11: 1, 1 — 7

Williams, Allan F.(2009) ‘Licensing Age and Teenage Driver Crashes: A Review of the Evidence’, Traffic Injury Prevention, 10: 1, 9 — 15

Related posts:

1. Too Young to Die
2. Fit To Drive
3. Pushing the Limit

According to a recent paper by Lee S. Friedman, Donald Hedeker, and Elihu D. Richter, the lifting of the federal 55 mph speed limit in 1995 was responsible for 12,545 deaths between 1995 and 2005. That’s about 45 percent more American fatalities than we have suffered in 9/11, Iraq and Afghanistan put together.

The freakonomics post by Eric A. Morris is worth reading , as is the link to Robert Yowell’s more skeptical article here.

Friedman’s paper cited above uses the Fatality Analysis Reporting System (FARS) to gather data on fatal road deaths which they correct for traffic volume and density. They found a 3.2% increase in road fatalities after the National Maximum Speed Law was repealed, allowing states to increase the limit above 55mph (90kph). From this they work out their figure of 12,545 deaths.

But before the US nannies (and the New Zealand nannies) start looking at reducing the speed limit further on roads, there are several things wrong with their conclusions. While it is perfectly true that the faster your speed the more likely you are to have an accident and the worse the accident will be, the evidence is that speed limits, of themselves, produce little reduction in the road toll. When the US introduced the 55mph limit in 1974 in response to the 1973 Oil Crisis, there was an immediate drop in road fatalities. This drop was, unfortunately, quite transient. It was also unsurprising that reducing high speed crashes in 1974 would have a serious impact on fatalities. Few seat belts, no roll bars, crumple zones or airbags – it is amazing anyone survived a high speed crash then.

Fast forward to today and even the cheapest, low-end car is an order of magnitude safer than the best 1974 car. For a high-speed accident to be fatal today you have to be either driving a very old car, ignoring the seatbelt alarm or driving very fast indeed. Head on collisions would be the other major cause of fatalities but these would be as fatal at 90kph as they would at 120kph (the difference between a 180kph and a 240kph collision is immaterial). I have long held the opinion that New Zealand’s poor road statistics has far more to do with our relatively ancient fleet of cars than it has to do with the speed limit (and don’t get me started on the pitiful state of our highways).

Modern cars do have one feature that makes fatal accidents more likely. They are fast. A decade of improving engines means that, again, even a low-end car can travel far in excess of any speed limit. There have been three fatal accidents on the road in front of my house in the past 5 years. None of the cars were doing anywhere near the posted speed limit of 80kph. My lowly Hyundai Sonata has a clock that goes to 220. While I suspect it might not quite hit the end of the speedo, I have no doubt that I could take the car close to the top. I would then be driving at double to speed limit (note to cops: I have never, ever tried this!). It seems to be that this ability to greatly exceed the speed limits is more likely to be the cause of the small increase in fatal crashes. The car might feel stable at those speeds but one bump in the road and you are flying.

Friedman’s paper does contain one interesting statistic. The urban interstates that have retained their original 55mph limit have by far the greatest increase in fatal accidents (12.88% – not quote in the abstract), while the urban interstates with slightly increased speed experienced a slight drop. The authors attribute this to speed adaptation and spillover effects that occur when drivers, coming off high-speed roads, continue to drive faster than those already on the same road. Although this is a well-observed phenomenon, there is no reason that this should cause an increase in fatalities over and above the increase on non-urban interstates. Admittedly the traffic density would be greater but this has already been controlled for in the statistics. I suspect what is happening is that drivers coming off the faster roads are becoming more impatient and are taking more chances. This would explain the improvement at slightly higher speeds.

It is easy to draw simplistic conclusions about figures such as speed and fatalities. But the problem is considerably more complex than more speed = more fatalities. Politicians do not like the complex, which probably explains why they are so ready to listen to superficial explanations such as this.

Related posts:

1. Mostly Nothing
2. Driving Impaired
3. One for the Road

Govt’s tough line on violence isn’t working – police

Police say the Government’s policies to reduce violent crime have had little effect, as such offending is still on the rise and last year’s murder rate was the highest in 10 years.

“Legislation changes during 2009 have generally had negligible impact on total recorded crime statistics,” say police papers obtained by One News.

“had negligible impact on total recorded crime statistics” is not the same thing as “Not working” at all. Not working implies that someone actually thought that such legislation would have an immediate effect on crime. Such thinking would make John Key look like a pessimist.

It should be obvious to all that any tougher sentencing will make little initial impact. This is because tougher sentencing is not a particularly great deterrent (although it does have a deterrent effect, albeit small), but it removes the worst criminals from society for a longer period of time, meaning that tougher sentencing will reduce crime, but only gradually, as criminals are caught.

Putting more police onto the Force will have the immediate effect of increasing certain types of recorded crime, particularly crimes that respond well to campaigns such as drink drinking and drug offenses. It is therefore hardly surprising that these have gone up.

Comments on the statistics tend to focus on the homicide rate which has increased. Firstly the homicide rate is a small part of the crime statistics and the raw number will tend to fluctuate from year to year. Cosgrove may call the figures a “damning indictment” on the Government, but it is hard to take his words as anything but politicking, as the previous Labour government presided over similar increases for nearly a decade. A decade’s worth of increases do represent a damning indictment on Labour, but it is far too early to start condemning National.

The second thing about the homicide rate, is that it is the rate that responds the least to legislation. After all, someone who is willing to take another’s life is unlikely to be thinking rationally about the consequences and will almost certainly be thinking that s/he will “get away with it”.  The deterrent effect of sentencing and increasing police numbers is virtually non-existent for murder.

It is absurd to expect the government to do anything useful about homicides, particularly child homicides. There is no way that any government intervention can restore our sense of the worth of another person’s life. For that, we have to take responsibility as a society. By this, I most certainly do not mean that society is responsible for a child’s murder – that is solely the responsibility of the child’s killer. But we are responsible for the value we attach to human life. Our casual attitude to the killing of foetuses and elderly people has eroded our sense of the worth of human life, as has the endless bombardment of murders – real and imagined – that come forth from the small screen in our living rooms. In addition, the destruction of hope caused by rampant welfarism has assured us a pool of the disaffected, for whom life is no longer valuable.

Note; I am not saying that every woman who has had an abortion, and every person on welfare, is a murderer, any more than I am saying that every person who watches TV is a homicidal maniac. But these things gradually chip away at our perception of the importance of human life – and the affect is cumulative.

New Zealand has one of the highest homicide rates in the world. Isn’t it time we looked at the real reasons why and stopped blaming the government?

Related posts:

1. Three Strikes and You’re In
2. Crime Statistics
3. Damned if you do, Damned if you don’t

The study had 250 medical students go through 158 RCTs from 94 advertisements using a modified version of the Chalmers’ score. Why medical students? Goldacre suggests amusingly that they are cheap! But the real reason is that the students had just completed the section of their study that deals with appraising evidence-based medicine. They were therefore about as able to judge the trials as an average GP, perhaps more so. They were given an objective scoring system to follow and they had no previous exposure to prescribing the drugs being advertised. This would have given an accurate, unbiased assessment of the worth of these trials without resorting to the use of statisticians or academics. This gives a good “real world” picture of the value of these trials, should a GP or hospital doctor have asked for them.

It comes as no real surprise that so few of the advertisements had decent clinical data to back them up. This has been a common finding in many studies including this large swiss study of 2068 adverts. Goldacre cites this excellent meta-analysis of 24 studies on this subject from the open access journal Plos One. Even as far back as 1992, the highly regarded Annals of Internal Medicine published this study whose conclusions included:

In 44% of cases, reviewers felt that the advertisement would lead to improper prescribing if a physician had no other information about the drug other than that contained in the advertisement.

The moral of the story being that when the drug rep or an advert makes a claim, always insist on reading the cited study. I have done this from the time of my graduation, nearly thirty years ago, and my impression is much the same as these studies. About half of the claims made by reps are verifiable. To be fair on the drug reps, most of them do not know how to judge a study and are just going by what they have been told. And they are almost always perfectly willing to find you a copy of the paper.

From an ethical point of view, I cannot see how any doctor could change his prescribing habits without at least assessing the claims made by pharmaceutical companies, formally. I know many of my colleagues take the recommendations of the specialists they use, relying on their judgement as to the worth of the product. I think this is not an unreasonable thing to do, as most specialists are more able to assess these claims than the average GP. However, I still make it a policy to assess papers myself, as even my specialist colleagues may not be immune to the lure of the shiny new pill on the market.

So what makes a paper a bad one? Essentially, bias in selection, lack of controls and low numbers. The first two are quite easy to spot once you know a little about the subject, the last is the commonest reason for considering a trial dubious. I can’t tell you how many times I have seen adverts claiming a great “P” value of 0.001 (That’s Probability, not Methamphetamine, BTW – anything less than 0.05 suggests that this is not a random chance). When you ask how many were in the study, you keep getting answers like 30 or 50. This means that it is dangerously likely that the result may simply be a type 1 error (the small sample has accidentally been taken from an abnormal part of the population – giving a spuriously significant result). This is a particular problem in medical trials. This is not to say that small trials are not worth doing, but that the result should always be treated with caution. Multiple small trials with the same result are much more reassuring, as is a large trial with a similar result.

Clearly adverts effect the way doctors prescribe drugs, otherwise drug companies would not run them. This is worrying considering that half of the claims made are either unverified or blatantly false. Prescribing medicine should be done on a purely evidence-driven basis. Prescriptions based on what pharmaceutical companies want you to believe, leave doctors open to charges that there is no more scientific basis to conventional medicine than to something like homeopathy. Worse, it could seriously disservice a patient, all in the name of the pharmaceutical company making another buck.

Doctors owe it to their patients to check out pharmaceutical company claims in full. It is stupid to accept the word of a person who has a vested financial interest in his product and it is nonsense to get our medical knowledge from the glossy brochures of drug reps.

Hat Tip:  David Whyte

Related posts:

1. Drug Market
2. First Aid
3. Can I Kill Vampires With it as Well?

The study, released Wednesday by the Pew Internet & American Life Project, found that 14 per cent of internet youths in the US, ages 12 to 17, now say they blog, compared with just over a quarter who did so in 2006. And only about half in that age group say they comment on friends’ blogs, down from three-quarters who did so four years ago.

Pew found a similar drop in blogging among 18- to 29-year-olds in the US.

The number of 30+ actually increased from 7% to 11% over 2007-2009. Seeing as I take exception to the label “old” being applied to 30-year-olds (30 being a distant memory for me), a more accurate title would have been “Are young people too vapid to blog?“.

To this I would answer a resounding “yes”!

This is not going to be a curmudgeon post. There will be no reminiscences beginning with “In my day…” I merely think that most people under the age of 25 live lives that have very little consistency. Youth has always been devoted to the moment with little thought of the future beyond daydreams. In today’s world of immediacy, where everything is literally at one’s fingertips, this tendency of young people has been exacerbated to a degree that makes patience an even less used virtue than chastity.

It is small wonder, therefore, that few people under the age of 30 have the patience to sit down at a computer and blog for a hour or so. Add the fact that young people appear to be surgically grafted to their cell phones and it is unsurprising that a medium like twitter – undoubtably the most inconsequential and ephemeral way of communicating ever invented – is the medium that most appeals to youth. It is hard to say something of consequence when you have stimulation and entertainment coming at you from all sides. 140 characters is more than enough.

After all, the thing that young people fear more than death is – boredom.

Related posts:

1. Licensed to Kill
2. Alcopopped
3. Multiple Gunshot Wounds to the Foot