Posts from June 2017 (28)

StatsChat has been going long enough that I can look back at stories I disparaged in the past and see how well they held up.

To begin with, an April 2012 story about a vaccine for heart disease that might be available within five years. It wasn’t.

There doesn’t seem to have been any real development of this vaccine. But there is a 2017  research paper that has a new promising approach to vaccinating against heart disease.

You might have seen a story in the Guardian (don’t click while you’re eating), headlined “Popularity of sushi has brought rise in parasitic infections, warn doctors“.

There’s a link (also not safe for dinner) to a single case report of anisakiasis in Portugal attributed to sushi. The case report says

Most of the cases were described in Japan due to food habits; however, it has been increasingly recognised in Western countries.2 ,3

If you follow those references, you find a report of 2 cases in Italy, due to marinated raw anchovies, and 25 cases in Spain, due to marinated raw anchovies.

Anisakiasis is now being diagnosed in western countries, but if we can believe the evidence behind this story the cases are mostly from traditional European food practices, not because of  sushi.

Q: Did you see cannabis is actually better for pain relief than opioids?

A: Not convinced.

Q: But 92%97% of patients said they preferred it! Even if they’d tried opioids! You’re not saying you know better than them, are you?

A: Imagine you had a survey of people who cycle to work, including lots of people who own cars.

Q: Ok.

A: What proportion of those people would say they’d choose to cycle to work instead of driving?

Q: I don’t know, I don’t drive.

A:  Imagine you had a survey of people who cycle to work, including lots of people who have perfectly good bus routes as alternatives.

Q: Ok.

A: What proportion of those people would say they’d choose to cycle to work instead of driving or taking the bus?

Q: A lot.

A: Maybe even 92%97%?

Q: Maybe.

A: The survey was of about 2000 current medical cannabis users. It’s not surprising they say it works.

Q: So it’s not true?

A: No, I think it quite like is true, or at least partly true — not for everyone, but for a lot of people.

Q: Then what’s the problem?

A: The survey provides almost no additional evidence that it’s true. I already thought it was plausible, but anyone who didn’t think that shouldn’t have had their mind changed by the survey.

Q: Ok, what would convince you? Do we need randomised trials?

A: That would be nice.

Q: And a pony?

A: Ok, ok.  More realistically, a cohort study that follows up a group of people starting to use cannabis for pain relief to find out what they end up preferring, rather than starting with people who prefer cannabis.  You could set that up somewhere were medical use was just being legalised, and it wouldn’t cost that much.

Team Ratings for Round 17

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 118 matches played, 71 of which were correctly predicted, a success rate of 60.2%.
Here are the predictions for last week’s games.

Predictions for Round 17

Here are the predictions for Round 17. 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.

• A map of 1.3 billion taxi trips in New York, taking advantage of the underappreciated principle that there’s no point having more detail than the screen can display.  Also, GPS error naturally gives an attractive glowing effect that you’d usually have to add in afterwards

• “In the summer of 2015, Alexandra Franco got a letter in the mail from a company she had never heard of called AcurianHealth. The letter, addressed to Franco personally, invited her to participate in a study of people with psoriasis, a condition that causes dry, itchy patches on the skin.”  A story about creepy data-mining, from Gizmodo.

• From Scientific American, graphics showing daily, weekly, yearly patterns in number of births.

• From the New York Times: a new drug for muscular dystrophy. It costs about US$1 million per year, and the FDA is not really convinced it has an effect

• It’s time for the NZ Garden Bird Survey, which means it’s time for me to recommend their questions and answers page for its attention to principles of experimental design.

• “Death when it comes will have no sheep”. Last week it was hamster names; this week it’s proverbs. Look, save yourself some effort and just go directly to Janelle Shane’s blog rather than waiting for each post to go viral.

• “In Science, probability is more certain than you think.” Chad Orzel

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 June 30 2017.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of June 24 – 30 2017 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…)

If you’d like to comment on or debate any of this week’s Stat of the Week nominations, please do so below!

I missed this a couple of weeks ago when it came out, but Stuff has a pretty good story on the ‘cheese addiction’ question.

As long-time readers will know, there’s been a persistent story circulating in the media claiming that a University of Michigan study found cheese was addictive because of substances called casomorphins.  The story is always unsourced (or sourced only to another copy), and the researchers at the University of Michigan have pointed out that this isn’t remotely like what their research found. The difference now is that Dr Neal Barnard, of the Physicians Committee for Responsible Medicine is fronting up. He’s written a book.

As the story on Stuff says (with added expert input), the cheese addiction claim doesn’t really stand up, but cheese is high in fat and there are things to not like about the dairy industry. And

While it’s not hard to pick holes in some of Barnard’s anti-cheese arguments, the book has good advice on what to eat instead

That could well be true but, as with paleo, you could find books that just give the recipes and leave out the scientifically-dubious propaganda.

Team Ratings for Round 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 111 matches played, 67 of which were correctly predicted, a success rate of 60.4%.
Here are the predictions for last week’s games.

Predictions for Round 16

Here are the predictions for Round 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.

Q: What’s brown and sticky?

A: A stick!

Q: What do you call a cow on a trampoline?

A: A milk shake!

Q: Where does chocolate milk come from?

A: Brown cows!

There’s a popular news story around claiming that 7% of Americans think chocolate milk comes from brown cows.

It’s not true.

That is, it’s probably not true that 7% of Americans think chocolate milk comes from brown cows.  If you try to trace the primary source, lots of stories point to Food & Wine, who point to the Innovation Center for U.S. Dairy, who point to Today.com, who point back to Food & Wine. Critically, none of the sources give the actual questions.  Was the question “Where does chocolate milk come from?” Was it “Lots of people say chocolate milk comes from brown cows, do you agree or disagree?” Was it “Does chocolate milk come from: (a) brown cows, (b) mutant sheep, (c) ordinary milk mixed with cocoa and sugar?” Was there a “Not sure” option?

This was clearly a question asked to get a marketing opportunity for carefully-selected facts about milk.  If the Innovation Center for US Dairy was interested in the factual question of what people believe about chocolate milk, they’d be providing more information about the survey and how they tried to distinguish actual believers from people who were just joking.

The Washington Post story does go into the more general issue of ignorance about food and agriculture: there’s apparently a lot of it about, especially among kids.  To some extent, though, this is what should happen. Via the NY Times

According to Agriculture Department estimates going back to 1910, however, the farm population peaked in 1916 at 32.5 million, or 32 percent of the population of 101.6 million.

It’s now down to 2%. Kids don’t pick up, say,  how cheese is made, from their day-to-day lives, and it’s not a top educational priority for schools.

The chocolate milk story, though, is bullshit: it looks like it’s being spread by people who don’t actually care whether the number is 7%.  And survey bullshit can be very sticky: a decade from now, we’ll probably find people citing this story as if it was evidence of something (other than contemporary news standards).