Stats Chat

From @LIVENewsDesk on Twitter, and then Stuff, we have record nominal prices for petrol.

Adjusted for inflation, the price is still definitely lower than in mid-2008, when it got to $2.18, which is $2.41 in today’s money, and driving is much cheaper than in was in the mid-1980s.

Also, neither Stuff nor the AA still seem to know about the government’s independent petrol-price monitoring system. Their estimate of the importer margin has been stable since May, but is well above recent historical levels.

The Royal Statistical Society has just commissioned an opinion poll to look at beliefs about policy-relevant issues and how they relate to reality.  The first few results:

1. Teenage pregnancy: on average, we think teenage pregnancy is 25 times higher than official estimates: we think that 15% of girls under16 get pregnant each year, when official figures suggest it is around 0.6%.
2. Crime: 58% do not believe that crime is falling, when the Crime Survey for England and Wales shows that incidents of crime were 19% lower in 2012 than in 2006/07 and 53% lower than in 1995. 51% think violent crime is rising, when it has fallen from almost 2.5 million incidents in 2006/07 to under 2 million in 2012.
3. Job-seekers allowance: 29% of people think we spend more on JSA than pensions, when in fact we spend 15 times more on pensions (£4.9bn vs £74.2bn).
4. Benefit fraud: people estimate that 34 times more benefit money is claimed fraudulently than official estimates: the public think that £24 out of every £100 spent on benefits is claimed fraudulently, compared with official estimates of £0.70 per £100.

You might look up what the actual figures are in New Zealand. To get you started, Paula Bennett claimed about $200 million in benefit fraud in 2010/11 (and about 10% of that was prosecuted) from about $9 billion, or about 22c per $100.

Team Ratings for Round 18

Here are the team ratings prior to Round 18, 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 126 matches played, 78 of which were correctly predicted, a success rate of 61.9%.

Here are the predictions for last week’s games.

Predictions for Round 18

Here are the predictions for Round 18. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Team Ratings for Round 20

This year the predictions have been slightly changed with the help of a student, Joshua Dale. The home ground advantage now is different when both teams are from the same country to when the teams are from different countries. The basic method is described on my Department home page.

Here are the team ratings prior to Round 20, along with the ratings at the start of the season.

Performance So Far

So far there have been 113 matches played, 79 of which were correctly predicted, a success rate of 69.9%.

Here are the predictions for last week’s games.

Predictions for Round 20

Here are the predictions for Round 20. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

From XKCD

Congratulations again to Nick Iverson for his nomination on newspaper headlines about cancer, which is worth a post all by itself. It’s no wonder people are feeling confused about medical advice when most days there’s new headlines with isolated findings:

“Oily fish twice a week is best breast cancer defence.”

Someone should have told Angela Jolie. She thought the best defence was total removal.

Anyway, the Herald previously told us “Biggest breast cancer risks – obesity, alcohol and lack of exercise.”

So make up your mind, Herald, is the biggest risk lack of fish or obesity, alcohol and lack of exercise?

By the way, salted fish is another Group 1 carcinogen. So presumably your oily fish mustn’t be salted. And it must be oily not fatty because “Fatty food linked to breast cancer”.

Other big breast cancer risks: “HRT doubles danger of breast cancer” and your risk is also doubled by NOT having a teen pregnancy.

Also being a professional almost doubles your risk “Professional women more susceptible to breast cancer”, and living in NZ doubles your risk “Breast cancer: Geographic links analysed”.

Not finished yet.

Air fresheners double your risk “Breast cancer link to air fresheners”; being left handed doubles your risk “Left-handed women’s risk of breast cancer higher”.

Taking vitamin pills adds 20% to your risk “Major research finds link between multi-vitamin pills and breast cancer”. Whew! That’s a relief. For a minute there I thought it was going to double my risk.

From Wonkblog at the Washington Post, a look at all the things that allegedly cost the US $BIGNUM in productivity, eg

– The fact that so many employees aren’t engaged with their jobs costs U.S. employers a staggering $550 billion per year.

– Parents stressed out about child care cost $300 billion per year in lost productivity.

– Cigarette smoking takes $92 billion per year out of the workplace.

– Then throw in insomnia, which costs another $63 billion per year.

– Let’s not forget excessive commuting, which costs employers $90 billion per year.

Adding up all of the losses gives $1.8 trillion per year. That’s about 12% of US GDP or about 2/3 of US federal government tax receipts.

Stuff has a story with the headline “More kids committing sexual abuse” and the lead

Easy access to increasingly hardcore pornography and the sexualisation of childhood are being blamed for a rise in the number of children sexually abusing each other.

However, if you actually read the story, the only real information is on number of prosecutions, and

 Police say the jump in prosecutions was due to better knowledge and increased reporting of sexual abuse, rather than a rise in incidents.

No other evidence or expert opinion is given to support the claim of a real increase in abuse, which seems to be entirely made up.

And while on the subject of factchecking, Netsafe chief technology officer Sean Lyons is quoted as saying

“You type ‘kiwi chicks’ into Google and the images that come back won’t be small feathered birds.”

I tried this. On the first page of results, eight links and the only image displayed were for small feathered birds, one was to a museum project “‘Kiwi Chicks: New Zealand Girl History/Ngā Kōhine Kiwi: He Hitori Taitamāhine o Aotearoa’”, and one was to a page at TheRockFM, which might offend some people but is not anything shocking for kids.

I got basically the same page using lmgtfy.com in a browser not logged into any Google services, so it isn’t just my pure and innocent search history that’s biasing the results.

Update: here’s the first screenfull of results from a Google image search for ‘kiwi chicks’

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 July 12 2013.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of July 6 – 12 2013 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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From the inimitable Dan Davies, a post on how often you’d expect all the front-page photos in major UK newspapers to be of white people

So a while ago on Twitter, I saw this storify by @KateDaddie, talking about ethnic minority representation in the British media, in the context of this article by Joseph Harker in the British Journalism Review. As I am a notorious stats pedant and practically compulsive mansplainer, my initial reaction was to fire up the Pedantoscope and start nitpicking. On the face of it, it is not difficult to think up Devastating Critiques[1] of the idea of counting “#AllWhiteFrontPages” as an indicator of more or less anything. But if I’ve learned one thing from a working life dealing with numbers (and from reading all those Nassim Taleb and Anthony Stafford Beer books), it’s that the central limit theorem will not be denied, and that simple, robust metrics with a broad-brush correlation to the thing you’re trying to measure are usually better management tools than fragile customised metrics which look like they might in principle be better.