Posts from February 2014 (45)

And they’re right.

The problem is they don’t know the difference between the words “astronomy” and “astrology”. So we get survey results like this,

A study released by the National Science Foundation finds nearly half of all Americans feel astrology—the belief that there is a tie between astrological events and human experiences—is “very” or “sort of” scientific. Young adults are even more prone to believe, with 58% of 18- to 24-year-olds saying it is a science.

Richard N. Landers, a psychologist in Virginia, thought the name confusion might be responsible, and ran a survey using Amazon’s Mechanical Turk, where you pay people to do simple tasks.  He asked people to define astrology and then to say whether they thought it was scientific.

What he found, is shown in this graph based on his data

People who think astrology is about horoscopes and predicting the future overwhelming don’t think it’s scientific — about 80% are in the ‘no’, and ‘hell, no’ categories. People who think astrology is about the solar system and stars  think it is pretty scientific or very scientific.

The data isn’t perfect — it’s from a much less representative sample than the NSF used — but there’s a very strong indication that confusion between “astronomy” and”astrology” could explain the otherwise depressing results of the NSF survey.

(via @juhasaarinen)

Some of you may be enough older than me to remember yoghurt as the miracle food of the 1970s. It seems to be back. From the Independent, this time, a Herald headline “Low fat yoghurt could combat type 2 diabetes”.

The research paper is open-access, at least for now, so I looked at it.  The first thing to note is that the research did not anywhere distinguish low-fat yoghurt from full-fat. All yoghurt was grouped together in all the analyses.

While the study could not prove a conclusive causal link between eating dairy and lower diabetes risk, the association was strong.

Not all that strong. Comparing high to low yoghurt consumption they only saw a 28% lower risk; the difference in risk was less when they included other “low-fat” fermented dairy products, and the evidence wasn’t all that overwhelming even before you take into account that they looked at 9 different subsets of dairy foods.

Stuff has a story about differences in coffee preference between regions of NZ.

A customer survey published yesterday confirms the capital has the country’s biggest coffee snobs – almost three in four will choose an expensive brew over a less tasty one every time.

They don’t give enough information to work out how big the differences are, or how they compare to the uncertainty in the survey.

There’s slightly more information in the press release — still no uncertainty, but we are told that the figure is 72% for Wellington and 67% for the country as a whole. Not a terribly impressive difference, and almost certainly the survey isn’t large enough to be able to tell which region is really highest. Fortunately, it’s not a question where the true answer matters.

You have to go to the Canstar Blue site to find that the survey population isn’t Kiwis in general, or even coffee-drinkers, but people who have been to a chain coffee store at least once in the past six months.

Interestingly, although 17% to 33% of people (varying between regions) consider coffee alone to qualify as breakfast, only 10% to 14% say they drink coffee for the caffeine.

Yeah, right.

Now Valentine’s Day is safely past in NZ, I can link to a post on It’s a Stat Life, a blog not entirely unlike StatsChat. Robin Evans writes:

A friend pointed me to this story about the average number of men (or rather frogs) a woman has to date before finding their ‘Prince Charming’ (apparently it’s 15).  Let’s leave aside for now how they came up with the number: I’ve no doubt the methodology conforms to the most rigorous standards that we’ve all come to expect from the internet.  I thought that this paragraph might give some people hope:

If you’ve made out with 11 men, great news! A new survey suggests you’re only 4 away from Prince Charming. On average, anyway.

It’s now my duty to crush that hope.

Team Ratings for Round 1

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons. Still the Crusaders have a high rating. Despite being tempted to arbitrarily change their rating, I have stuck with the formula. You may wish to downgrade them. The replacement of the Kings by the Lions provides another problem. In the past I have given a rating of -10 to an unknown team entering the competition, and this has seemed to provide reasonable predictions. The Lions do have a rating from when they were previously in the competition so I have used that rating. Again, you may wish to lower their rating.

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

Predictions for Round 1

Here are the predictions for Round 1. 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.

• Genetic determinism, from Nathaniel Comfort: Studying genetics and popularization over the last century or so has led me to the surprising conclusion that genetic oversell is independent of genetic knowledge. We see the same sorts of articles in 2014 as we saw in 1914.

• Kudos to the Herald for explicitly saying that research on grapeseed extract in colon cancer was lab-based, not on people. This sort of science is interesting if it isn’t hyped up as a cure.

• Rather less impressive is the ‘sextacy’ story on the evils of Viagra. This combines general warnings on psychological problems; the specific, well-characterised dangerous interaction between Viagra and nitrates; and relatively anecdotal warnings about serotonin syndrome. And rubbish about arginine, where the fact that it gets sold in early February is taken as convincing evidence it has genuine sexual effects. Guess where the Herald got the story.

• Our resident Savage Bayesian would probably like me to link to this story about the evils of p-values. It’s quite good, as far as it goes.

There’s a new paper in The Lancet, summarising population-based surveys across the world that asked about non-partner sexual violence. The paper’s conclusion, from the abstract

Sexual violence against women is common worldwide, with endemic levels seen in some areas, although large variations between settings need to be interpreted with caution because of differences in data availability and levels of disclosure.

The story in Stuff has the headline Sexual assaults more than double world average, and starts

The rate of sexual assault in Australia and New Zealand is more than double the world average, according to a new report.

After several highly publicised rapes and murders of young women in India and South Africa, researchers from several countries  decided to review and estimate prevalence of sexual violence against women in 56 countries.

The results, published in the UK medical journal The Lancet, found that 7.2 per cent of women aged 15 years or older  reported being sexually assaulted by someone other than an intimate  partner at least once in their lives.

The study found that Australia and New Zealand has the third-highest rate, more than double the world average, with 16.4  per cent.

If you look at the raw numbers reported in the paper, they showed Australia/NZ at about ten times the rate of the Caribbean or southern Latin America or Eastern Europe, which is really not plausible. Statistical adjustment for differing types of survey reduced that margin, but as the researchers explicitly and carefully point out, a lot of the variation between regions could easily be due to variations in disclosure, and it suggests that rape is being underestimated in some areas.

As usual with extreme international comparisons, the headline is both probably wrong and missing the real point. The real point is that roughly one in six women in Australia & NZ report having experienced sexual violence.

This is what it looks like when a country does manipulate its official statistics (from Ezequiel Tortorolli, via Tom Pepinsky and Xavier Marquez).

The black line is Argentina’s official federal inflation rate. The red line is the average of the rates for the 18 provinces, which are the fainter wiggly lines.

[Update: Argentina has just announced a new inflation index that’s supposed to be non-bogus. It will take a while to convince people.]

The Herald has a headline “Why internet adultery numbers are soaring“, but doesn’t actually say why, or even provide any real evidence that they are increasing.

The news is that the number of people signed up to the website AshleyMadison is increasing as they expand internationally, but we’re not given any indication that the number of active members in a given area is increasing, let alone any data on how much actual goings-on is going on. So, the only internet data in the story would be relevant in the business section of the paper, but the Herald has the story filed under “Relationships & Pets.”

There is a gesture towards data later in the story

According to figures in the Journal of Marital and Family Therapy, some 22 per cent of men and 14 per cent of women will cheat on their spouses at least once during their marriage.

but this is basically useless for the headline claim about numbers soaring, since these are one-time percentages, and we aren’t even told when or where they are from. It looks as though they are probably from this 2005 paper, which summarises data back to the 1980s.

On the positive side, though, this is enormously better than the one from two years ago which had astonishingly bad use of data, completely ignoring denominators

If your partner supports National, has a PC, drinks Coke, eats meat, has a tattoo, smokes and is a Christian, be warned – they could be a cheater.

Progress, of sorts.

There’s an interesting story in the Herald about research on the combined cost of commuting and housing in Auckland.

“If you just look at housing costs alone, outlying areas appear really affordable and it initially seems to make sense to say, hey, let’s open up greenfield sites on the urban periphery and develop here,” Mr Mattingly said. “But when you include these broader costs, they are not as affordable as they seem.”

This is the sort of conclusion I like to see, as a non-driver, so I looked at the research paper (there wasn’t a link, but the Herald did give the researchers’ names and journal name). I was disappointed that the impact of commuting costs wasn’t higher, at least until you got out to Pukekohe or Warkworth.

Since the journal is published by a company known for its dedication to preventing knowledge being disseminated for free, I won’t show any whole maps, but here are the central chunks of the cost maps with and without commuting costs. Or perhaps the other way around.