Stats Chat

• From Wired, 13 of the best infographics from 2013. Not entirely convinced, though I quite like the pie charts showing colour changes by Impressionist artists over time.

• Rachel Kumar is a data scientist who tests fitness trackers:  she still says “it’s unclear how you use this data. I know if I’ve been active or not, and the histograms don’t tell me anything else.” 
• Algorithms: “They have biases like the rest of us. And they make mistakes. But they’re opaque, hiding their secrets behind layers of complexity. How can we deal with the power that algorithms may exert on us? How can we better understand where they might be wronging us?” by Nicholas Diakopoulos.
• An example: according to a new rating of Faculty Media Impact, MIT’s top department is Sociology. MIT doesn’t actually have a sociology department.

The Herald tells us

Sunscreen provides 100 per cent protection against all three types of skin cancer and also safeguards a so-called superhero gene, a new study has found.

That sounds dramatic, and you might wonder how this 100% protection was demonstrated.

The study involved conducting a series of skin biopsies on 57 people before and after UV exposure, with and without sunscreen.

There isn’t any link to the research or even the name of the journal, but the PubMed research database suggests that this might be it, which is confirms by the QUT press release. The researcher name matches, and so does the number of skin biopsies.  They measured various types of cellular change in bits of skin exposed to simulated solar UV light, at twice the dose needed to turn the skin red, and found that sunscreen reduced the changes to less than the margin of error.  This looks like good quality research, and it indicates that sunscreen definitely will give some protection from melanoma, but 100% must be going too far given the small sample and moderate UV dose.

I was a also bit surprised by the “so-called superhero gene”, since I’d never seen p53 described that way before. It’s n0t just me: Google hasn’t seen that nickname either, except on copies of this story.

A good story in Stuff today about mortality rates.

A Ministry of Health report shows while death rates are as low as they have even been since mortality data was collected, men are far more likely to die of preventable causes than women.

Heart Foundation medical director Professor Norman Sharpe said it is a gap that will continue to widen as a “new wave” of health problems caused by obesity start showing up in the statistics.

The latest mortality data, gathered from death certificates and post-mortem examinations, shows there were 28,641 deaths registered in New Zealand in 2010.

While the number of actual deaths is increasing, up 8 per cent since 1990, this was because of a growing and ageing population.

Death rates overall have dipped about 35 per cent, meaning statistically we are more likely to survive to a ripe old age.

There aren’t any of the problems I complained about in last year’s story on this topic: there’s a clear distinction between increases in rates and the impact of population size and aging, and the story admits that the problems with preventable deaths it raises are projections for the future.

While on this topic, I will point out a useful technical distinction between rates and risks.  Risks are probabilities; they don’t have any units and are at most 100%. Lifetime risks of death are exactly 100%, and are neither increasing nor decreasing.  Rates are probabilities for an interval of time; they do have units (eg % per year). Rates of death can increase or decrease, as the one death per customer is spread out over shorter or longer periods of time.

There’s an interesting (and open-access) paper in the journal PLoS One that I would have expected to attract more media attention both for its results and for its visualisations.

The researchers looked at words that distinguished people by age and gender (or, to be precise, what they had told Facebook were their age and gender). Here’s the female half of the graphic showing male/female distinguishing words (the full image, here, ‘contains language’)

The clump in the middle are the words that are the most effective evidence that the writer is female. That doesn’t mean these words are especially frequent in women’s Facebook posts, just that they are much less frequent in men’s posts. The green clumps are the most-distinguishing topics, as identified statistically, with the words that define those topics.

Analyses like this are bound to come up with results that look like a caricature, since they are obtained in much the same way that a caricature is drawn, by finding and highlighting the most extreme and distinctive aspects.

• There’s not as many of you as we thought: the new Census figures are out with the total population. There will be no new Maori-roll electorate, but the North Island will get a new general-roll electorate. Fortunately, the NZ redistricting procedure is very boring, compared to, say, Pennsylvania. Election nerds are reduced to arguing about the potential impact on electorates such as Epsom.
• All the more-interesting results from the Census are still to come: here’s their release timetable
• The US did not get its monthly unemployment figures last month, because the Bureau of Labor Statistics is shut down. Pew Research has a list of the other data the government won’t be releasing
• A couple of articles from the online magazine Nautil.us: one on statistics in the courtroom (US-oriented, but still interesting) and one on coincidences.
• Almost coincidentally, James Curran is giving a public lecture this Thursday, 7pm, on forensic statistics: his professorial inaugural lecture.  Everyone welcome.

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 October 11 2013.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of October 5 – 11 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 3News tonight, spoiling a story that was otherwise accurate and reasonable (if one-sided).

A new bridge in the Auckland suburb of Bayswater cost the Auckland Council $2.5 million. It would be about the same to bridge the gap between the minimum wage and a living wage for council staff.

The bridge is a one-off cost; the wage increase is an annual cost. This isn’t a sensible comparison.

Given the preoccupations of the Auckland media this week a better comparison would be to the $3 million quoted as the savings for not mowing the berms in the old Auckland City area (especially as these savings are presumably achieved partly by not paying the type of contractor who currently gets less than the ‘living wage’).

There’s an interesting story in Stuff today about an increased risk of death in people who drink lots of coffee. One of the interesting things about it is that the Herald has the same story about two weeks ago. And when I say “the same story”, I mean almost word for word the same AAP story.  I wasn’t convinced then (neither was Andrew Gelman), and it hasn’t gotten any more convincing.

The other interesting thing about the story is that the research paper was published in Mayo Clinic Proceedings. “What’s interesting about Mayo Clinic Proceedings?”, you ask, having never heard of it.  That’s my point. There are some scientific journals whose press releases you’d expect the media to monitor, and you’d expect to see stories about research papers with popular appeal. Mayo Clinic Proceedings is not really one of those journals, and it isn’t clear how this research came to the attention of AAP.

More brilliance from XKCD:

From today’s New Zealand Herald:

Beauty giant Dove has been forced to take an advertisement for its shampoo off television screens after it was deemed misleading to viewers.

The commercial for Dove Hair Care, which claimed 90 per cent of Kiwi women recommend its products, received a number of complaints from viewers who said it was “clearly misleading”.

 The people “polled” had been sent free samples. Had I been one of them I would have made nice noises too.

Read the full story here.