Posts filed under Just look it up (285)

Following up on the discussion of green coffee extract and unsupported health claims, I’d like to point out two links.

The Nightingale Collaboration is a British initiative to oppose  unsupported health claims by making complaints to various regulatory bodies.  This includes the Advertising Standards Authority, but also the professional councils that regulate various health professions.  For example, the General Chiropractic Council regulates chiropractors in the same way that the General Medical Council regulates medical doctors, and both have a duty to investigate complaints of, say, misleading advertising by their members.

In New Zealand the main resource would be the NZ Advertising Standards Authority.  They have details of the Advertising Codes (which were formulated by advertisers and media, not handed down from above), and complaint procedures, including an online complaint form.  If you honestly believe an advertiser is making an unsupported health (or environmental, or financial) claim, you can file a complaint explaining why. Your part in the process is now over. All complaints are reviewed by the Chairman, and if there is potential merit to the claim, the advertiser has to respond:

The Advertising Standards Authority’s complaints process operates on the basis that the Advertiser must provide substantiation/evidence to support the claims made in their advertising. Therefore, if a complaint is made that an advertisement is misleading or deceptive, it is the responsibility of the Advertiser to provide sufficient information to enable the Complaints Board to assess the accuracy of claims or statements made.

Last year I filed a complaint about a website selling green tea extract, and the process seemed to work.

Stuff’s story starts out

Half of all Kiwis like to change jobs regularly, with 51 per cent of people surveyed by online recruiter Seek starting their current role less than two years ago.

I don’t see why “like to change jobs regularly” is remotely the same as “have changed jobs recently”, and I’m sure people who were laid off in the recession or lost jobs to the ChCh quake would agree.  But, more importantly, Stats New Zealand collects real data on changes of employment, so why not use that rather than a non-random sample from what Seek has in previous years described as “a broad online audience”. 

In fact, Seek doesn’t do too badly in estimating: the true figure is 54%, with the difference being only about twice the margin of error for a random  sample of the size of their previous years’ surveys.

As usual, I’m having to rely on previous years’ press releases for any methodology information, since Seek hasn’t posted this year’s one and Stuff isn’t giving any details.

There’s a headline in the Herald: Heart disease linked to non-stick cookware: study. There seems to have been some loss in translation for both the article and the headline.

The journal press release says

Exposure to perfluorooctanoic acid (PFOA), a manmade chemical used in the manufacture of some common household products, appears to be associated with cardiovascular disease and peripheral arterial disease in a study of 1,216 individuals

That is, PFOA is used to make non-stick cookware, but cooking with non-stick cookware isn’t an especially important source of it, and the article doesn’t say it is.

Unlike the Teflon in non-stick coatings, which is as inert as a very inert thing, PFOA is quite chemically interesting. There are traces of PFOA in all sorts of things, and it accumulated in the environment, which is why it’s interesting to public health researchers.  If you want to read more, Wikipedia is a bit alarmist about the health evidence but reasonably informative.

The story goes on to say

From a statistical point of view it’s strange  that the researchers just used four years of NHANES data, from two non-adjacent two-year periods.   The study keeps going year after year, and they are now measuring PFOA and related compounds on greater numbers of people.  As a service to the StatsChat readership, I just spent 15 minutes downloading and analysing the 2007-2008 data, which has PFOA measurements on 2100 people, 80 of whom reported coronary heart disease.  I didn’t do as thorough a job of ruling out other risk factors (such as cholesterol or high blood pressure), but it’s still interesting to note that there is absolutely no sign of an association between coronary heart disease and PFOA levels in the 2007-2008 data.

An annoying trope in US political stories (which, fortunately, hasn’t made it here yet) is to criticise a politician for using too many first person singular pronouns — saying “I” and “me” too often.  These stories often get analysed by the computational linguists over on Language Log, who tiredly point out that the claim is (a) largely irrelevant to the point being made, and (b) false.

This week’s example is the speech by New Jersey Governor Chris Cristie at the Republican National Convention.  A New York Times piece said

Gov. Chris Christie is getting rave reviews today for his performance at the National Republican Convention, and there’s no doubt in my mind that he did a huge amount of good for the three most important people in his life – he, himself, and him….

By my count, Mr. Christie used the word “Romney” six times in his address. He used the word “I” 30 times, plus a couple of “me’s” and “my’s” tossed in for seasoning.

but as Mark Liberman points out, the actual use of first person singular pronouns was slightly lower than in the speeches by Paul Ryan, Anne Romney, Rick Santorum, Mike Huckabee, and much lower than Clint Eastwood.  It’s also slightly lower than in the similar speech by (then Illinois Senator) Barack Obama at the 2004 Democratic Convention.

At Simply Statistics, a set of stat/data related startups.

One that looks interesting for teaching and for data journalism purposes is Statwing, which is building a web-based pointy-clicky data analysis system, aiming to have good graphics and good text descriptions of the results.  This is the sort of project where the details will matter a lot — poking around at their demo there were a few things I was slightly unhappy about, but nothing devastatingly bad, so there is potential.

The Herald has a good story today about attitudes to depression (unfortunately, only in Australia, but you can’t have everything).

Judging from the information on the beyondblue website about the 2001-2 survey, this is a real survey using random telephone sampling.  It’s asking important questions, and the Herald’s story summarises the worrying level of ignorance about depression among Aussies.  Notably, “62 per cent wrongly believe antidepressant medication is addictive” — the problem is the reverse, these medications are often difficult to keep taking for the necessary extended periods of time.

I said that I was judging from the information about the 2001-2 survey.  The webpage was last updated in 2006, and it says they are looking to do a second survey in 2004. Some more Googling suggests that they did a second survey in 2007-8, but I can’t find any results.  The media releases page doesn’t say anything, and the most recent release listed is from a month ago.

In the modern world it’s a pity that organisations can’t be more consistent about posting for the rest of us the information that they send out to the media. Then we might even have more success in persuading the media to link to it.

StatsChat has been mentioned again by National Business Review, though they attribute StatsChat to Stats New Zealand.  They are using my post on cybercrime to attack the proposed internet anti-bullying laws.   Personally, I’m not convinced my post supports their argument, but you can judge that for yourselves.

One thing I will point out: that $625 million cybercrime number that I criticized and that they are now disparaging? They used it in a headline as recently as June.

The US Census Bureau estimates that the population of the United States reached π×100 million on Tuesday afternoon (US time): 314,159,265. (via Stuff)

There’s no margin of error with this estimate, which might seem surprising from a respected national statistics agency.  The reason is that there is no sampling error in the estimate, all the uncertainty is from non-sampling errors.   The Census Bureau started with the 2010 US Census counts, subtracted deaths and emigrations (me, for example) and added births and immigrations.  In principle, the data on all these is complete and no sampling is used.  That doesn’t mean there isn’t any error — far from it — but it does make it very hard to estimate how much error there is.

The ubiquity of non-sampling error, and the impossibility of estimating it accurately, explain why surveys in New Zealand are about the same size as surveys in the USA, despite the huge difference in population.   In theory, you could afford to collect larger samples in the US, so US statistical agencies could get more precise estimates than Stats New Zealand can afford.  In practice, once surveys get to a certain size, the non-sampling error starts to be more important than the sampling error, and extra sample size stops giving you much increase in accuracy.

From Stuff

BP spokesman Jonty Mills said as prices neared uncharted territory it was likely demand would drop. The outlook for prices remained volatile, he said.

An Automobile Association spokesman, Mark Stockdale, said prices were now “perilously close” to a record, which typically prompted a review of driving options and habits.

As usual this is talking about nominal prices, not inflation-adjusted, so the real prices aren’t really as ‘perilously close’ to a record as all that.  Dividing the StatsNZ petrol price index by CPI we get:

Prices are much lower than in 1985,  and still safely below the more recent 2008 peak.  The record that is in peril is the little wiggle in prices from last year.

On the other hand, prices are up at the levels of the 1980s (though with much cheaper cars), so driving really is getting more expensive.  A “review of driving options and habits” might be a good idea

The aphorism that adorns StatsChat is actually a paraphrase, by the statistician Samuel Wilks in a 1951 speech, of what H.G. Wells wrote.  The full paragraph from Wells’  Mankind in the Making (1904) is

Modern, too, is the development of efficient mathematical teaching; so modern that for too many schools it is still a thing of tomorrow. The arithmetic (without Arabic numerals, be it remembered) and the geometry of the mediaeval quadrivium were astonishingly clumsy and ineffectual instruments in comparison with the apparatus of modern mathematical method. And while the mathematical subjects of the quadrivium were taught as science and for their own sakes, the new mathematics is a sort of supplement to language, affording a means of thought about form and quantity and a means of expression, more exact, compact, and ready than ordinary language. The great body of physical science, a great deal of the essential fact of financial science, and endless social and political problems are only accessible and only thinkable to those who have had a sound training in mathematical analysis, and the time may not be very remote when it will be understood that for complete initiation as an efficient citizen of one of the new great complex world-wide states that are now developing, it is as necessary to be able to compute, to think in averages and maxima and minima, as it is now to be able to read and write. This development of mathematical teaching is only another aspect of the necessity that is bringing the teaching of drawing into schools, the necessity that is so widely, if not always very intelligently perceived, of clearheadedness about quantity, relative quantity, and form, that our highly mechanical, widely extended, and still rapidly extending environments involve.

In 1904, it was reasonable to describe the analytic techniques needed to make `endless social and political problems’ accessible and to achieve `clearheadedness about quantity, relative quantity, and form’ as “mathematics”.  Today we would usually call these “statistics”, although “numeracy”, or “don’t they teach you anything in school these days” would also be possible translations.

It’s also worth emphasizing, for the benefit of those seeing change and decay in all around, that teaching these basic calculating and thinking techniques in public schools was something Wells was proposing as a major reform in education.