Good story in the Herald about a randomized trial of Vitamin D supplementation being run in New Zealand. Healthier people tend to have higher vitamin D levels in their blood, but for other vitamins this hasn’t turned out to mean that supplements are helpful. We don’t know for vitamin D, and we need to find out.
Long-time readers may remember that I’m betting against the vitamin, but I’d be very happy to be proved wrong.
For anyone who wants to read more coverage
I thought I saw a Stuff story, but I can’t find it now.
Update: Ivan Oransky, of Embargo Watch, has found more sources to confirm the dodgy embargo and has a post on it.
The Herald tells us
Having a purple bedroom could enhance your sex life, according to a new study.
with red and sky blue coming in next in line. Beige/white/grey colours are apparently at the bottom of the list. We aren’t told anything about how the survey was done, but we are told it was sponsored by UK retailer Littlewoods, who would be happy to help you redecorate. If the association were true, it would almost certainly be in the opposite direction, but there isn’t much reason for us to believe it’s true.
In fact, it doesn’t seem as if even Littlewoods really believe their survey. If you look at their decorating suggestions pages, the bedrooms are mostly pale and beigey, with the colours suggested for kids’ bedrooms.
Brad DeLong points out (mixed in with lots of other stuff) out how carefully you have to state things to get to the famous 47% of non-taxpaying Americans: Last year 47% of tax units paid no net federal income taxes.
Precise questions can matter a lot.
You’ll probably be seeing local stories about GM corn and the weedkiller Roundup coming out soon. Here’s an overseas example. I was asked for comment on the research paper by the NZ Science Media Centre, and said
I do not think the herbicide risks look convincing, especially with respect to cancer. There is no consistent pattern in deaths with dose of either Roundup or GM corn: this is not just showing a threshold, as the authors suggest, since in all six of their comparisons the highest-dose group has lower mortality than lower-dose groups. The hypothesis of hormone-related cancer differences is not supported by the multivariate biochemical analysis, which found differences in salt excretion but not in testosterone or estradiol. The strongest conclusion that could be drawn from this study is that it would be worth studying a larger group of controls than just 10 and (since there is no sign of dose-response) just a single low dose of Roundup or GM corn.
The researchers say “It is noteworthy that the first two male rats that died in both GM treated groups had to be euthanized due to kidney Wilm’s tumors”. This is noteworthy, but perhaps not in the way the researchers mean: increases in human Wilms’ tumor from GM corn or herbicide residues would already be obvious even at rates hundreds of times lower than reported in these rats.
At the time, I had only read the research paper, not any of the media stories. There is a detail in the story I linked above that is absolutely outrageous:
Breaking with a long tradition in scientific journalism, the authors allowed a selected group of reporters to have access to the paper, provided they signed confidentiality agreements that prevented them from consulting other experts about the research before publication.
That is, we’ll let you have a scoop provided we can make sure there’s no risk of getting it right or disagreeing with us. Embargoes on stories about scientific papers are standard, but one of the justifications is to precisely to provide journalists with time to get the facts right. It would be interesting to know how many of the journalists who signed these agreements were willing to admit to it in their stories.
That’s how I first heard the theory that it’s safer to sit at the back of a plane than at the front. It turns out there’s something to it: back in 2007, Popular Mechanics magazine looked at data on all the US plane crash fatalities over 35 years and found a roughly 40% higher risk of death in front of the wing.
Stuff is now reporting on a British TV stunt, where a plane full of crash-test dummies was deliberately crashed in the Sonoran Desert. The test found that the front of the plane experienced higher accelerations, so you would be better off near the back. It also found that the brace position helped. This, of course, applies to only one form of plane crash — the ‘controlled flight into terrain’, and only to a subset of those. In some crashes no-one dies; in others everyone dies.
The conclusion that economy class is safer in general is much more dubious. It can’t be much safer, since the chance of dying in a ‘fatal air incident’ is very, very, very small wherever you sit (Wikipedia claims about 1 per 10 million journeys). Crashes are only a subset of fatal incidents, and the benefit of sitting near the back must be substantially smaller even than this. As a comparison, on an 8+ hour flight, the chance of pulmonary embolism is about 16 times higher than the chance of dying in a fatal air incident, and nearly 50 times high for a 12+ hour flight, so a relatively small reduction in risk in first class would outweigh any crash benefit.
Ben Goldacre has a new book, “Bad Pharma”, coming out next week. I was checking to see if the Auckland city library had ordered it:
Indeed they have. Also, I found out that they have a graphical search tool for looking at connections between possible search terms. Just like Google’s Knowledge Graph, only not. Clicking one of the orange words (eg, albacore or goldmine) takes you to another set of connections: albacore, hardcore, Vegemite, lockdown, toast, Screwtape,.. the possibilities for free association are endless).
In the map below(via), of extrapolated obesity rates in the US in 2030, one state stands out
Does Colorado have the highest predicted rate? No, that’s down in the South-East. The lowest rate? Again, no, that’s further west. Colorado is just the pinkest state, because of infelicitous colour choices.
Here are the team ratings prior to the Preliminary Finals, 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.
| Current Rating | Rating at Season Start | Difference | |
|---|---|---|---|
| Bulldogs | 6.65 | -1.86 | 8.50 |
| Sea Eagles | 6.61 | 9.83 | -3.20 |
| Rabbitohs | 6.38 | 0.04 | 6.30 |
| Cowboys | 6.35 | -1.32 | 7.70 |
| Storm | 5.67 | 4.63 | 1.00 |
| Raiders | 1.12 | -8.40 | 9.50 |
| Knights | 0.01 | 0.77 | -0.80 |
| Dragons | -0.37 | 4.36 | -4.70 |
| Broncos | -0.98 | 5.57 | -6.50 |
| Sharks | -2.05 | -7.97 | 5.90 |
| Titans | -2.20 | -11.80 | 9.60 |
| Wests Tigers | -2.74 | 4.52 | -7.30 |
| Roosters | -5.43 | 0.25 | -5.70 |
| Panthers | -6.45 | -3.40 | -3.00 |
| Warriors | -8.08 | 5.28 | -13.40 |
| Eels | -8.25 | -4.23 | -4.00 |
So far there have been 198 matches played, 121 of which were correctly predicted, a success rate of 61.11%.
Here are the predictions for last week’s games.
| Game | Date | Score | Prediction | Correct | |
|---|---|---|---|---|---|
| 1 | Sea Eagles vs. Cowboys | Sep 14 | 22 – 12 | 3.77 | TRUE |
| 2 | Rabbitohs vs. Raiders | Sep 15 | 38 – 16 | 7.44 | TRUE |
Here are the predictions for the Preliminary Finals
| Game | Date | Winner | Prediction | |
|---|---|---|---|---|
| 1 | Storm vs. Sea Eagles | Sep 21 | Storm | 3.60 |
| 2 | Bulldogs vs. Rabbitohs | Sep 22 | Bulldogs | 0.30 |
Luis Apiolaza has an interesting post on suicide statistics in Canterbury, where he examines the Coroner’s comments that suicide rates decreased after the quake.
He compares the actual counts of suicides since 2007 to a purely random sequence of counts with the same mean (a Poisson process), and doesn’t see much difference: one of the panels below shows the real data, and the other four show data with no pattern.
Another way to look at the same thing is with cumulative sums, used in industrial process control: the dots are cumulative sums of actual minus average suicides, and the dashed lines in the background are ten simulated versions of the same thing, with no true pattern. Again, the real data doesn’t stand out as different.
These analyses answer the question “Is there evidence of changes in suicide rate in Canterbury some time in the last five years?”, saying “Not really”. However, if we know when the February earthquake was, and we know that lower suicide rates (and also crime rates) are often seen after natural disasters, we can ask if the Canterbury data are consistent with that expectation. They are, as the Coroner observed, but if you didn’t already have that expectation, the data wouldn’t provide much evidence for it.
The data don’t speak for themselves: you have to ask them questions, and the choice of question matters.