Posts from March 2012 (64)

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 March 23 2012.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of March 17-23 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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On 3 News last night, we got a tour of South Auckland, just missing various drunken disturbances.   The video starts “3News has uncovered some shocking figures about the amount of alcohol some offenders are drinking” , and the webpage story says  “new research has revealed the alarming impact alcohol is having on crime“.

That’s approximately truish.  The `new research’ is a report dated December 2010 by the New Zealand Drug Use Monitoring (NZ‐ADUM) research programme at Massey University.  They surveyed 800 arrestees in Whangarei, Auckland Central, Wellington Central, and Christchurch Central, asking them about their drug and alchol use.   And there was a lot of drug and alcohol use — evidently, police arrests are selecting for people who are insufficiently risk-averse in all sorts of ways.  The figures possibly qualify as ‘shocking’, with arrestees reporting an average of 12 standard drinks both on typical days when they drink, and on the day they were arrested.  Some people reported much higher consumption, and some reported none.

3News compares this to “The average New Zealander drinks around two standard drinks a day”, which looks like this StatsNZ figure on total alcohol sales.  In addition to the problems of comparing self-reported drinking with sales data, the national average is over all days and the arrestee average is over days when they drank.  Since the arrestees reported drinking an average of about 1 day in 3, the correct comparison to 2 drinks/day is 12/3=4 drinks per day, about twice the NZ average.    The arrestees also consumed more tobacco, more cannabis, more P, more opioids, more ecstasy, and more of everything else than the average Kiwi; in fact, as far as I can tell alcohol showed a smaller difference than any of the other drugs — mostly because the average for all New Zealanders is fairly high.

The other notable statistic about drinking is that the average drinks per day that they drank was the same as the average drinks on the day they were arrested.  That is, although many of the arrestees were drunk when they were arrested, they were no drunker than they usually are on about one day in three.   The relative risk of arrest given their heavy drinking for these arrestees is thus about 3, which is a lot smaller than I would expect even without the headlines.  If you read the report, while alcohol is unquestionably a problem, it is far from the only problem that the arrestees have.

This isn’t in the NZ media yet, but it will probably turn up soon.  A second CERN experiment, ICARUS,  has repeated the measurement of neutrino speed made by the famous OPERA experiment: the same neutrino source, the same distance, but different measurement equipment.   And the neutrinos arrived on-time, not 60ns early. Since the OPERA results violate relativity  and have other practical and theoretical problems , it’s not that hard to decide which set of numbers to believe.

As Prof. Matt Strassler says

This is the way it works in science all the time. A first experiment makes a claim that they see a striking and surprising effect. A second experiment tries to verify the effect and instead shows no sign of it. It’s commonplace. Research at the forefront of knowledge is much more difficult than people often realize, and mistakes and flukes happen on a regular basis. When something like this happens, physicists shrug and move on, unruffled and unsurprised.

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

It’s not often that you see a special interest group make a claim about the economic impact of their chosen problem and think “I never imagined it could be so small”.

Today is, apparently, World Sleep Day, and we have a problem

A quarter of New Zealanders have a chronic sleep problem, according to the World Association of Sleep Medicine.

Studies by the World Association of Sleep Medicine show sleep disorders cost New Zealand at least 40 million dollars a year in lost productivity

A quarter of (working-age) New Zealanders is a bit under a million people, so that’s an average of about a buck a week, or about five minutes per sufferer per week at minimum wage.   Can lack of sleep really be that unimportant economically, or has someone dropped a decimal place somewhere?

Actual numbers from entertainment industry lawyers and lobbyists form the basis for this, frankly, unbelievable talk about Copyright Math(TM).

http://www.ted.com/talks/rob_reid_the_8_billion_ipod.html

While this talk may seem amusing, the figures he quotes are used to justify all sorts of real world implications for you and I. The Copyright (Infringing File Sharing) Amendment Act came into power last year, the US Embassy attempted to write Section 92A for New Zealand, and now new trade agreements are being negotiated.

Next time you see unbelievable claims, specifically of a numerical nature, question the figures.

And remember to insure your music collection. It’s worth billions.

Team Ratings for Round 3

Here are the team ratings prior to Round 3, along with the ratings at the start of the season. I have created a brief description of the method I use for predicting rugby games. Go to my Department home page to see this.

Performance So Far

So far there have been 16 matches played, 8 of which were correctly predicted, a success rate of 50%.

Here are the predictions for the games so far.

Predictions for Round 3

Here are the predictions for Round 3

Team Ratings for Week 4

Here are the team ratings prior to Week 4, along with the ratings at the start of the season. I have created a brief description of the method I use for predicting rugby games. Go to my Department home page to see this.

Performance So Far

So far there have been 21 matches played, 12 of which were correctly predicted, a success rate of 57.1%.
Here are the predictions for the games so far.

Predictions for Week 4

Here are the predictions for Week 4. The prediction is my estimated points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Roy Morgan have released their “State of the Nation” report, and the Herald has two stories. In the first

According to the Roy Morgan State of the Nation March 2012 report, there has been an upsurge in the number of New Zealanders who consider Maori culture to be an “essential component” of New Zealand society.

The other story says that most of NZ wealth is now  held by over-55s.

the 55-plus group has increased its share of net wealth from 43 per cent in 2002 to 52 per cent last year.

that is, by about a quarter

Their share of the population also rose in the same period, but only from 19.5 per cent to 24.7 per cent.

or, about a quarter.   Based on these numbers, in 2002, the average net wealth for people over 55 was about 2.2 times higher than the average for everyone over 14, and it’s now about 2.1 times higher.  Since the story goes on to say

The value of their own homes accounted for 56 per cent of their wealth a decade ago, and 70 per cent last year.

presumably the ratio for non-home wealth is even less favorable to the over-55s.

The Herald did a good job itself in providing statistics to put today’s front-page story in context

BREAST CANCER

2700 number of new cases in 2008

624 number of deaths in 2008

8: number of women who had something unspecified wrong with their diagnosis, for reasons we don’t give, having unknown impact on their future health, in circumstances that are still being investigated but might not be exciting enough for the front page if we wait for the facts.