Stats Chat

• With some insurance companies taking advantage of exercise trackers like FitBit to discriminate in favour of the health, there’s a potential market for fooling your FitBit. It’s hard to tell if UnfitBits is serious, but someone will be.

• When you might not want the government to have high-quality evidence-based choice of policies

• The pitfalls of using Google n-grams for linguistic research, from Wired
  

• The Sveriges Riksbank Prize in Economic Sciences in memory of Alfred Nobel went to Angus Deaton. Here’s a readable example of his writing, on why the poverty line is the same everywhere in the US.

Team Ratings for the Quarter Finals

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the Rugby World Cup.

Performance So Far

So far there have been 40 matches played, 34 of which were correctly predicted, a success rate of 85%.
Here are the predictions for last week’s games.

Predictions for the Quarter Finals

Here are the predictions for the Quarter Finals. The prediction is my estimated expected points difference with a positive margin being a win to the first-named team, and a negative margin a win to the second-named team.

Team Ratings for the ITM Cup Finals

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 7 matches played, 5 of which were correctly predicted, a success rate of 71.4%.
Here are the predictions for last week’s games.

Predictions for the ITM Cup Finals

Here are the predictions for the ITM Cup Finals. 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 the SemiFinals

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 40 matches played, 29 of which were correctly predicted, a success rate of 72.5%.
Here are the predictions for last week’s games.

Predictions for the SemiFinals

Here are the predictions for the SemiFinals. 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.

One News had a story tonight about elephants. This is how it starts

NZ anchor: An American researcher thinks he may have come up with a new weapon in the fight against cancer, inspired by a trip to the zoo. He remembered that elephants almost never get cancer and wondered whether what protects them could also help us.

US reporter: Elephants have survived 55 million years on this earth. They’ve evolved to beat cancer, and they might just help us beat it too

That’s a nice story, but it’s basically backwards from the more-plausible story in Nature News, and the (open-access) paper in JAMA.

The distinctive feature of elephant blood, according to either version of the story, is that elephants have many more copies of the tumour-suppressor gene p53. This gene makes a key protein in the mechanism that causes cells with DNA damage to kill themselves rather than reproducing and turning into tumours.  A large proportion of tumours have mutations in p53, and people who inherit a damaged copy of the gene tend to develop cancer (including some unusual forms) early in life.  We’ve known about p53 for a long time — decades — so while it is a target for drug development, it isn’t by any means a new target.  We haven’t got far with it because it’s hard to mimic the effect of a protein that acts inside the cell nucleus.

The story in Nature News is that the American researcher, Dr Jordan Schiffman, specialises in treating children with familial cancer, including ones who have inherited mutations in p53 (Li-Fraumeni syndrome). He heard a talk about elephants having many copies of p53. He then went to his local zoo to find out what the cancer rate was in elephants, and confirmed it was low.   This is important;  lots of people will tell you that sharks, for example, don’t get cancer, and that’s just not true.  Elephants, on the other hand, really do seem to have a surprisingly low rate of cancer.

Since elephants have a lot of cells and live a long time, you’d expect them to have a lot of chances to get cancer. Studying elephants makes sense as a way to find completely new ways of treating or preventing cancer. Unfortunately, it seems that a major reason elephants don’t get cancer  is that they have lots of redundant p53 genes, which isn’t a new treatment target. (Other reasons may be that they don’t smoke and they eat vegetarian diets.)

So, while it’s true that elephants have multiple copies of the p53 gene, everything else in the story is basically backwards. Looking for new cancer treatment targets in elephants is a good idea, but that’s isn’t quite what they did. The findings are good news for elephants but they are bad news for us; p53 isn’t a promising new treatment target, it’s one of the oldest ones we have.

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 16 2015.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of October 10 – 16 2015 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.

(more…)

Q: Did you see there’s a giant rock with the potential to end life on Earth?

A: This one?

Q: Yes. Are they exaggerating?

A: Depends what you mean. In a sense it does have the potential to end human life on Earth, but it would have to actually hit Earth to do that.

Q: But it’s  “similar to the 1862 Apollo asteroid which was classified as a potentially hazardous object”

A: Similar except for being a lot further away. As the story says, “Potentially Hazardous Objects” approach closer than 7,402,982km, and this one is about 25 million km away at its closest.

Q: That’s an awfully precise number, 7,402,982, isn’t it? Why do they need it to the nearest kilometre?

A: They don’t. It’s 0.05 Astronomical Units, and whoever did the conversion doesn’t understand about significant digits. Wikipedia, for example, rounds it to 7.5 million km.

Q: And the other really precise numbers? It says the asteroid is moving at 64,374km/hr, but surely the speed will change more than 1km/hr because, you know, gravity and physics and stuff?

A: That’s 40,000 miles per hour. Again, looks like one significant digit in the original.

Q: So how far away is this asteroid compared to, say, the moon?

A: To one significant figure, 100 times further away.

Q: That’s quite a lot. Why is NASA making a fuss about this asteroid?

A: They aren’t. They issued a press release about asteroid rumours in  August, headlined “There is no asteroid threatening Earth“.  The NASA @asteroidwatch twitterwallah is getting a bit tetchy about the whole thing.

Q: Does the asteroid have something to do with the “blood moon” we had recently?

A: Only in the sense that they were both completely unsurprising and harmless astronomical events.

(h/t @philiplyth)

Yesterday I wrote about a ‘gay epigenetics’ story in the Herald, and wasn’t convinced that there was anything worth publicising at this point, and that there wasn’t enough detail to interpret the results.

Ed Yong, a science journalist who was actually at the conference, has a story today in the Atlantic. He fingers the conference as the responsible party for the publicity (here’s their press release), though with the active cooperation of the researchers.

His story has more detail and makes it clear that there’s very little evidence, and more importantly that the lead researcher knew this:

“The reality is that we had basically no funding,” he said. “The sample size was not what we wanted. But do I hold out for some impossible ideal or do I work with what I have? I chose the latter.”

For pilot research presented to consenting scientists that might be reasonable, but for press releases it isn’t.

Epigenetics is an area of science where New Zealand has an international reputation. It would be a pity if it ended up as one of the areas where you can be sure that basically nothing that makes it to the newspapers is true.

From the Herald (from the Telegraph)

Factors ranging from exposure to certain chemicals to childhood abuse, diet and exercise may affect the DNA controlling sexuality, according to research being presented at a US conference on genetics.

…

They believe they can predict with 70 per cent accuracy whether a man is gay or straight, simply by looking at those parts of the genome.

[There’s a slightly better story in Nature News.]

70% accuracy doesn’t seem all that impressive. Using the usual figures on the proportion of men who are gay, the approach of assuming everyone is straight unless you are told otherwise is better than 90% accurate, and doesn’t need expensive genetics.  Presumably they mean something different by 70% accuracy, but we don’t know what.

More importantly, this is research in identical twins.  If you take pairs of people who are genetically identical, had the same environment in the womb, and then very similar environments in infancy and childhood, you’ve stripped out nearly all the other factors that could affect sexual orientation. That’s the point of doing the research this way — you get a clearer view of potentially-small differences — but it’s a limitation when you’re trying to make claims about people in general.

Also, there’s an important difference between genetics and epigenetics here. The epigenetic markers, as the story says, can be affected by things that happen to you during childhood. But that means we can’t necessarily assume the correlations between epigenetic differences and sexual orientation are causal.  The “factors ranging from exposure to certain chemicals to childhood abuse, diet and exercise” that can affect epigenetic markers could also affect sexual orientation directly — especially since the epigenetic markers were measured in cells from the lining of the mouth, not in, say, the brain.

On top of all that, this is another annoying example of research being publicised before it’s published. It’s not at all impossible that the claims are true,  but there isn’t enough public information to tell. The research was presented at the conference of the American Society for Human Genetics. People at the conference would have been able to see more detail, and maybe ask questions. We can’t. We won’t be able to until there’s a published research paper. That would have been the time for publicity.

And finally, there’s an interesting assumption revealed in the headline “Boys ‘turned gay by childhood shift in genes’“. The research looked at differences between identical twins. It says absolutely nothing about which twin changed and which one stayed the same — you could equally well say “Boys turned straight by childhood shift in genes”.

Quartz has an interesting analysis of a recent Twitter storm over abortion, triggered by the US Republicans’ attempts to defund Planned Parenthood.  The headline is striking “How to tell whether a Twitter user is pro-choice or pro-life without reading any of their tweets.”

The writers describe how they could use words in twitter profiles to predict people’s attitudes.  They also found that social network structure was a very strong predictor: people shared the views of those they followed.  They write “so polarized is the social network structure that even very basic, obvious characteristics stop mattering if we know who your friends are”

It might seem strange that you could do so well in predicting attitudes across multiple countries on a controversial topic. It would be strange, except that the data they used was restricted to a small group of people who were participating in a Twitter argument about abortion. The story admits this, but not until near the end.

In real life, you probably can’t learn that much about someone’s views on abortion by whether they tweet about cats or football. In the context of a small, highly polarised argument, you probably can.  In real life, people don’t necessarily agree with the views of the people they follow on Twitter, but in that context it’s not surprising that they do.  And in real life, if someone wants to find out your views on a controversial topic they’d probably be better off asking you than tracking down all your friends and asking them.