Posts from December 2016 (27)

We had a Stat of the Week nomination for this graph from Stuff showing attitudes to democracy changing for people born more recently:

The complaint was that the non-NZ lines were indistinguishable. They do get pop-up descriptions on mouse-over, but the coloured circles in the legend are certainly not doing much work.

This is the original graph, from the New York Times:

The Times verison is more elegant and clearer, and also provides uncertainty intervals around the lines. On the other hand, the higher-than-wide panels are going to make any decrease look more dramatic.

There are two more important problems with the graph. The first is that it uses only the highest category, “Essential”, on a ten-point scale.  A decrease in the proportion of people using the top rating could be due to the whole distribution moving down, but it could also just be a trend in people’s tendency to use the extreme values on a scale.

Here’s a related graph using other data, tweeted by (Prof) Pippa Norris

The trend looks weaker when using means on a four-point scale. It’s also less universal than the New York Times graph suggests.

There’s another problem, though.  The source for the first graph: Yascha Mounk and Roberto Stefan Foa, “The Signs of Democratic Deconsolidation,” Journal of Democracy. The paper doesn’t exist yet at the journal’s website (or anywhere else that I’ve been able to find).  According to Dr Mounk’s CV, it’s coming out in the first edition next year.

Part of the point of peer-reviewed publications is that they include the details that don’t make it into a media story. This is, potentially, significant research on an important topic. If we’re going to have a full-on panic about millennials and the end of democracy, we could at least wait a couple of months for the research to be published.

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 December 9 2016.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of December 3 – 9 2016 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!

It’s worth remembering sometimes that the Daily Mail is far from the worst UK paper statistically, and that US election polling and reporting could be a lot worse.

There was a by-election today in the electorate of Richmond Park. The Liberal Democrats won, with 49.7% of the vote to ex-Conservative Zac Goldsmith’s 45.2%.

Last month On Monday, the Evening Standard published a poll showing Goldsmith was leading 56% to 29%.

On Tuesday, the Standard reported as controversial a claim that the Liberal Democrats were “within three to four points” of Mr Goldsmith, with a Conservative source saying  “These are the usual claims from the LibDem national by-election machine – that’s not what we are finding on the doorstep.”

From the Herald

Obviously there isn’t research giving ‘the exact time you will crash your car’.  What you might hope for is the time at which you (more precisely, the average NZ driver) are at highest risk.  We don’t even get that.

The comparisons are for totals, and as the story admits, more crashes happen in peak times because more people are driving.  It’s worse than that, though. The story says

…22,000 collisions occur annually in the afternoon peak up to 6pm. This then drops to just 2000 crashes a year at 11pm and a mere 800 at 1am.

The 22,000 is over 3-hour periods and I think the 2000 and 800 are for single-hour periods — I can’t tell for sure, because there’s no link to the original source, and I can’t find it on the IAG website.

Perhaps more relevantly for the New Zealand Herald, you have to read down to paragraph 11, which begins “Across most states…” to get the first solid indication that this story is about another country.

It’s from news.com.au, which explains why the handling of numbers isn’t up to local standards.

• A tool based on statistical modelling and summarisation (or, as they call it, AI) for large-scale discussion: pol.is, how it has been used in Taiwan, how part of the graphical display works (via @teh_aimee)

• Beautiful pictures of food popularity over season and year, based on Google Trends data (via @kamal_hothi)

• Elves are not pre-attentively perceived

• Despite the Sydney Morning Herald, Sydney high-school kids did not synthesise Daraprim. They synthesised pyrimethamine, and the difference is what matters. First, there’s the manufacturing quality control criteria that they don’t come close to meeting. More importantly, though, there’s the whole regulatory failure that let Shkreli overprice his brand of the drug in the US. In New Zealand, for comparison, Pharmac buys pyrimethamine for less than a dollar a pill, and in Australia it’s about the same (maybe cheaper).

• Herald Insights data visualisations about the Mt Roskill by-election

• Figure.NZ has a ‘festive data calendar’ with one NZ fact each day

• In the past few months, global mean temperatures have decreased. Or even “plummeted”
  
  That’s because it’s winter in the northern hemisphere, and the northern hemisphere has more land than the southern hemisphere, and land temperatures vary more with season than ocean temperatures. It happens every year, and no-one would take this year’s fall as special evidence against climate change. Except, apparently, the US House of Representatives Committee on Science, Space, and Technology (or at least their Twitter account)

Q: Did you see scientists have found a way to predict immediate death?

A: What? Lack of pulse?

Q: Very droll. No, it says interleukin-6. What is that?

A: It’s a messenger protein that some white blood cells use to stimulate other white blood cells to do stuff. If there’s a lot of it around, there’s probably inflammation, which is probably bad.

Q: And it’s new?

A: No.

Q: The story says it’s new.

A: Yes. Yes, it does.

Q: So what’s new?

A: Interleukin 6 and another marker of inflammation called C-reactive protein used to be thought of as the best things to measure if you cared about inflammation. Some researchers came up with another, called α₁-acid glycoprotein, and said it was better. This research is arguing that, no, α₁-acid glycoprotein isn’t better.

Q: Why isn’t α₁-acid glycoprotein mentioned in the story?

A: It is: the Herald’s just having font problems and calling it Î±1-acid glycoprotein.

Q: Are they right? Is interleukin 6 really better than α₁-acid glycoprotein?

A: We can’t really tell just from this one study, any more than we could really tell α₁-acid glycoprotein was better from the study that liked it.

Q: How accurate is the prediction?

A: Well, suppose you were given the name of  a 55-year old and had to guess whether they’d die in the next five years. What would you guess?

Q: Umm. No?

A: Very good. In this study, over 98% of the people didn’t die in the first five years of followup, so you’d be about 98% accurate knowing nothing.

Q: And knowing their interleukin 6 levels?

A: About 98% accurate.

Q: So it’s useless?

A: No, not at all. Comparing people at the top and bottom of the middle 50% of the distribution for interleukin-6 was like comparing smokers to non-smokers for short-term death rate. It’s just that will you/won’t you die in five years is not the right question for reasonably healthy middle-aged people.

Q: So it could be important for insurance, then?

A: In principle, if you wanted to undermine the usefulness of insurance.  It’s more useful for science — either understanding how inflammation has its effects, or trying to rule it out as an explanation of a correlation.