Posts from November 2012 (71)

That’s lead, Pb, the element. The Herald has a headline “Dangerous lead levels in Aussie kids – experts”. The article says

Health experts are calling for new national guidelines amid fears that up to 100,000 young Australian children could have dangerously high levels of lead in their blood.

The new proposed law for ‘natural remedies’ will provide some limits on health claims: they must be supported by scientific evidence or traditional evidence.  It’s depressing that this has to be considered an improvement over the current situation.  It’s also unfortunate that there is a special exemption for the largest category of health claims that have support neither from tradition nor science: homeopathic remedies (invented in 1796).

If ‘traditional’ evidence required a tradition of use of the product in essentially the form being sold and for essentially the indication being marketed, I wouldn’t object.  So, for example, it’s reasonable to say that ginger has been used traditionally in China to stop coughing, because it has. Many people would consider this sufficient reason to buy and use ginger for coughs, and I don’t see why there’s a vital national interest in deterring them.  What should be stopped is the ability to claim that a treatment is known to work simply because it has been traditionally used, and the ability to make up new ‘traditional’ uses for marketing convenience.

In the end, the impact of the law will depend on regulations and enforcement, not on statute.

Requiring ‘scientific evidence’ won’t get us very far without standards for the level of evidence required.  As StatsChat readers know, a huge variety of plant extracts have been shown to kill cancer cells in test tubes, or affect biochemical measurements in cell cultures. Newspapers are willing to take this as sufficient basis for stories and headlines claiming ‘can prevent cancer’ or ‘is helpful in treating diabetes’. If the proposed Authority takes a similar view, almost anything will be allowed.

Enforcement is also critical.  In theory, the US requires vendors to have scientific evidence for claimed health effects of natural remedies, but in practice they can get away with almost anything, because the FDA doesn’t have the resources for enforcement and there’s no practical way for private citizens to act. At the moment, the NZ Advertising Standards Authority has the ability to remove ads making health claims for which the vendor cannot supply evidence, and they have the willingness to act on public complaints from anyone who is unhappy about misleading health claims. The new law’s requirement for prior notification of health claims could strengthen enforcement, or weaken it, depending on how the requirement for evidence is interpreted.

Each week, we would like to invite readers of Stats Chat to submit nominations for our Stat of the Week competition and be in with the chance to win an iTunes voucher.

Here’s how it works:

• Anyone may add a comment on this post to nominate their Stat of the Week candidate before midday Friday November 9 2012.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of November 3 – 9 2012 inclusive.
• Quote the statistic, when and where it was published and tell us why it should be our Stat of the Week.

Next Monday at midday we’ll announce the winner of this week’s Stat of the Week competition, and start a new one.

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If you’d like to comment on or debate any of this week’s Stat of the Week nominations, please do so below!

This wind map (click to embiggen) is from hint.fm, who we’ve linked to before.  It shows the national short-term forecast wind grid, just after Sandy crossed the coast.  For scale, the distance between Boston (top right) and Charlotte (bottom) is almost exactly the distance between Auckland and Invercargill

It’s Nerdnite time again, Tuesday night, 6:30pm, at Nectar (470 New North Rd, above the Kingslander).

The speakers this time:

•  Cather Simpson, director of the Photon Factory, on lasers
• Matthew Dentith, epistemologist, on conspiracy theories
• Mike Dickison, giant flightless bird fancier, on why birds aren’t larger.

Incidentally, if you aren’t one of the 58273 people who have seen Mike Dickison’s hilarious presentation “Paedomorphic flightlessness and taxonomic affinities of an enormous Recent bird”, what are you waiting for?

Once again, NZ homes are at record nominal asking prices.

The real estate industry doesn’t make it easy to do inflation adjustment, but according to this, the average asking price in May last year of $429k  was 2% above the previous month and ‘just topped’ the October 2007 level that was when Realestate.co.nz started publishing the statistic. That means the October 2007 national average asking price was between $420k and $429k.

Suppose you bought a house in October 2007 for $420k and sold it now for the national average asking price of  $445,529.  Those 2007 dollars are worth about $479k  in today’s money, so you would have lost 8%, or about $34,000 in 2012 dollars.   That’s before taking into account maintenance, insurance, interest, and transaction costs.  The conclusion is about the same if you compare to an index of average wages: all these are helpfully provided by the Reserve Bank’s inflation calculator.

The comparison for Auckland may be more favorable — I can’t find what the 2007 average asking price was, but if it was below $535000, then we are at a new peak (or the top of a new bubble).

In May last year, Stuff had a good article on house prices and inflation, and even an infographic that told you more than ‘up’ or ‘down’, but that seems to have been an exception.

Frances Woolley at Worthwhile Canadian Initiative has another fascinating graph.  This one’s based on US data from the World Values Survey, where people were asked which income decile they are in:

As she describes, it doesn’t seem to be that the survey has accidentally undersampled the poor and the rich.  People seem to be deluded about where their income fits in the national distribution.

There are a number of possible explanations.  At the high end, there is the fact that people with more money than you are more visible, so it’s easy to overestimate how many of them there are.  At the low end, part of the explanation may be that young people whose family income has been higher in the past and will be higher in the future place themselves higher up in the distribution. The obvious example is university students, who in some ways behave more like their parents than like non-students with similar household income.

Part of it, though, is that people just overestimate how normal they are, just as  you (and I) probably overestimate how many people care about statistics in the media.

For those of you who have been living in a cave on Mars with your eyes closed and your fingers in your ears, the US is having a presidential election.

Nate Silver, a former baseball nerd who has climbed to fame by computing averages of opinion polls, said earlier this week that  Obama had a 72% chance of winning.  Old-fashioned political pundits disagreed, saying the race was too close to call (they also accuse Silver of just computing averages of opinion polls).

Andrew Gelman, a stats professor at Columbia University, has an opinion piece in the New York Times explaining what 72% means:

What I’m saying is that I can simultaneously (a) accept that Obama has a 72 percent chance of winning and (b) say the election is too close to call. What if the weatherman told you there was a 30 percent chance of rain — would you be shocked if it rained that day? No.

For Kiwi readers, a useful analogy might be rugby.  The All Blacks have beaten Australia in 70% of their games overall, and 75% in NZ.

Surveys really are the best way to get free advertising space.

Speight’s did some sort of survey of Kiwi men, and it’s turning up all over the place. They asked 504 men some incompletely described set of questions with no hint as to how they were selected.

Highlights of the results:

• A staggering 97% claim they would pay the correct amount of money when buying from an honesty box.  We can conclude that men who are financially dishonest also lie on surveys.
• Just over 80 per cent said they would help a stranded motorist on the road, but in Otago only 76 per cent said they would stop to lend a hand.  If there are 504 respondents across the country, you might wonder if there are enough in any one region to distinguish 76% from 80%.  No way.

The press release quotes Anna Gestro from Speight’s as saying  “The Speight’s survey is a small insight into the Kiwi male psyche.” 

How small? Very, very small.