Stats Chat

If you want to get a health story into the papers it helps if it sounds controversial and it especially helps if it tells people they can eat food they want to eat: thus the frequency of stories about chocolate, wine, and beer.

This week’s version is a not-very-detailed abstract from a conference in the US that purportedly says healthy food gives you lung cancer. And when I say that’s what the study purportedly shows, I mean:

• MSN: Eating fruits, vegetables and whole grains may increase chance of early onset lung cancer
• The Independent: Eating more fruits and vegetables could put you at risk for this cancer
• Newsweek: Fruits and Vegetables May Increase Your Cancer Risk, New Research Shows
• and even the researchers’ own press release: Eating fruits, vegetables and whole grains may increase chance of early onset lung cancer

One exception is Ars Technica, headlining the story as Absurd study suggests eating fruits and vegetables leads to cancer.

The press release says

“Our research shows that younger non-smokers who eat a higher quantity of healthy foods than the general population are more likely to develop lung cancer,” said Jorge Nieva, MD,

and, no, it really doesn’t show that.  For a start, we shouldn’t really be advertising  health advice to the general public based on just a conference abstract, with so little detail. In this case even the limited detail we have is enough to say that this shouldn’t be a big health story.

The research is part of a project to study lung cancer in younger people who don’t smoke. It used to be that nearly all lung cancer cases were in older people who had been smokers, but one of the victories of global public health is to reduce the number of cases like this.    Clearly, if someone has lung cancer at age 30 it isn’t because they’ve been smoking for fifty years — and in fact, many of them haven’t smoked at all. So, there’s interest in studying what causes their lung cancer.  The Epidemiology of Young Lung Cancer study wants to look at genetic attributes and environmental risk factors for lung cancer before age 40.

Finding a control group is hard. You can’t just recruit a whole bunch of young people and see who gets lung cancer, because it’s an very rare disease: you won’t find anyone.  You need to look for diagnosed cases, but then you need to decide who to compare them to. In this research the people with lung cancer were compared to people in a big national survey series, NHANES, which asks about diet.

The primary reported finding is that young people diagnosed with lung cancer had healthier diets (according to one measure) than the average of the US population.  The researchers don’t say they expected to see this, and my guess is they didn’t.  Their theory is that pesticides — in some generic holistic sense — are responsible.  It’s obviously not impossible that pesticides could be carcinogenic, but this doesn’t seem like a very good way to find out. In particular, while the people in the study all have lung cancer, they don’t all have similar mutations in their tumours  — they don’t have the same sort of lung cancer — and there’s literally zero actual data on pesticides, just an assumption that they’re present in healthier food, so this isn’t picking out some sort of ultra-selective cancer effect.

Everything here is correlations, but better correlational studies with controls consistently find that people with lung cancer eat less of the fruit and vegetables and high-fibre foods than people without lung cancer (eg here). There’s a theoretical argument that a diet high in anti-oxidants might reduce the body’s ability destroy cancer, but you wouldn’t look at a small, unusual subset of lung cancers to study this question.  There are perfectly good alternative reasons why the young lung cancer patients might have healthier diets than the US average. They’re young, for a start.  They have had their cancers diagnosed early enough to end up in a study like this one, which will correlate with income and interest in medical science. They’re non-smokers.

If unreliable evidence of a healthier diet in a subset of people with lung cancer is taken as evidence of harm from pesticides, should we take evidence of a less healthy diet in other groups of people with serious illness as evidence that pesticides are beneficial?

Team Ratings for Week 8

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 54 matches played, 39 of which were correctly predicted, a success rate of 72.2%.
Here are the predictions for last week’s games.

Predictions for Week 8

Here are the predictions for Week 8. 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 8

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 56 matches played, 30 of which were correctly predicted, a success rate of 53.6%.
Here are the predictions for last week’s games.

Predictions for Round 8

Here are the predictions for Round 8. 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 Week 11

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 48 matches played, 32 of which were correctly predicted, a success rate of 66.7%.
Here are the predictions for last week’s games.

Predictions for Week 11

Here are the predictions for Week 11. 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 14

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 65 matches played, 47 of which were correctly predicted, a success rate of 72.3%.
Here are the predictions for last week’s games.

Predictions for Round 14

Here are the predictions for Round 14. 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 22

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 147 matches played, 114 of which were correctly predicted, a success rate of 77.6%.
Here are the predictions for last week’s games.

Predictions for Round 22

Here are the predictions for Round 22. 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 Week 16

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 120 matches played, 82 of which were correctly predicted, a success rate of 68.3%.
Here are the predictions for last week’s games.

Predictions for Week 16

Here are the predictions for Week 16. 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 the NZ$ Herald New Zealand ranks among world’s top five wealthiest countries per capita in rich list report. I don’t think it really makes sense to call this a “rich list” report, but New Zealand does indeed rank “among” the world’s top five wealthiest countries (obviously we’re in fifth place, otherwise we’d be “among” the top four).

As Damien Venuto at Stuff notes, this doesn’t sound right. Is NZ really wealthier than Norway or Denmark or Japan or the UK?

The report being quoted is here; nobody links. There are at least three things going on.

First, the numbers are means when we usually prefer medians for this sort of comparison. The means are much more strongly influenced by the richest people, and also are just larger.  The use of means isn’t some evil capitalist plot by Allianz — it’s just easier to find out the mean, since you get it by taking the total and dividing by the population.  Working out the median per capita financial assets would take some serious survey-based research.  I will note that they aren’t completely clear about how they define the population, but it won’t make much difference to comparisons.

The second issue, which is important in the Stuff piece, is that a big chunk of the ‘wealth’ in New Zealand and Australia is over-valued real estate.  Real estate is problematic for wealth because it’s hard to extract the wealth that is nominally generated and use it to pay for stuff.  It’s even harder for large chunks of society to extract their real-estate wealth, since doing so would tend to bring prices back in line with reality.

A third issue, especially when comparing with the USA on one hand and the Scandinavian countries on the other hand, is what expenses need to be covered by that wealth.  In the USA, private assets pay for a larger fraction of healthcare and education than they do in New Zealand, and in turn we pay privately for more of these than they do in Norway.  When the public sector provides less, it will tend to use less  money, leaving private households more money to spend on the services they now have to buy.   The per-capita mean is not the best statistic for tracking this sort of thing: distribution of wealth and income matters.

As a final note, there is a whole chapter on distribution in the report that neither NZ paper mentioned.  The chapter isn’t very positive — inequality between between countries seems to have stopped decreasing, and it hasn’t improved within countries either.

Team Ratings for Week 10

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 43 matches played, 29 of which were correctly predicted, a success rate of 67.4%.
Here are the predictions for last week’s games.

Predictions for Week 10

Here are the predictions for Week 10. 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 7

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 48 matches played, 25 of which were correctly predicted, a success rate of 52.1%.
Here are the predictions for last week’s games.

Predictions for Round 7

Here are the predictions for Round 7. 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.