Posts from March 2016 (44)

Auckland commuters know the frustration well: You’re waiting for a bus, and the electronic board shows it’s three minutes away. Ten minutes later, you’re still standing there, wondering what’s going on. Or the board may say a bus is 10 minutes away – but it suddenly turns up when you’re not paying attention.

Department of Statistics doctoral student Tom Elliott, pictured, also knows that irritation well – he was once a regular bus user – and his PhD research aims to come up with a model that leads to better predictions. Read the full story here.

The Herald (and/or the Otago Daily Times) say

 New Zealand is the fifth most literate country in the world.

and

New Zealand ranked higher than Germany (9), Canada (10), the US (11), UK (14) and Australia (15).

Newshub had a similar story and the NZEI welcomed the finding.  One of the nice things about the Herald story is it provides a link. If you follow that link, the ratings look a bit different.

There are five other rankings in addition to the “Final Rank”, but none of them has NZ at number five.

So, where did the numbers come from? It can’t be a mistake at the Herald, because Newshub had the same numbers (as did Finland Today, and basically everyone except the Washington Post)

Although nobody links, I did track down the press release. It has the ranks given by the Herald, and it has the quotes they used from the creator of the ranking.  The stories would have been written before the site went live, so the reporters wouldn’t have been able to check the site even if it had occurred to them to do so.  I have no idea how the press release managed to disagree with the site itself, and while it would be nice to see corrections published, I won’t hold my breath.

Underlying this relatively minor example is a problem with the intersection of ‘instant news’ and science that I’ve mentioned before.  Science stories are often written before the research is published, and often released before it is published. This is unnecessary except for the biggest events: the science would be just as true (or not) and just as interesting (or not) a day later.

At least the final rank still shows NZ beating Australia.

Team Ratings for Round 3

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 17 matches played, 10 of which were correctly predicted, a success rate of 58.8%.
Here are the predictions for last week’s games.

Predictions for Round 3

Here are the predictions for Round 3. 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 2

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 8 matches played, 6 of which were correctly predicted, a success rate of 75%.
Here are the predictions for last week’s games.

Predictions for Round 2

Here are the predictions for Round 2. 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.

My first Listener column, a couple of years ago was on the US gender pay gap and what it does and doesn’t mean. It’s now open-access.

Stuff has a story under the lead

Now that it’s autumn, flu season isn’t far off and there’s plenty you could be doing in the kitchen to give your body that extra oomph for the cold months ahead.

Sadly they don’t mean making a phone call to book a flu vaccine shot: they have a list of herbs and spices with unsupported health claims.

Take the first, cinnamon.  Stuff says “It is high in antioxidants, is an anti-inflammatory and has an effect in lowering blood sugar.”  The  National Center for Complementary and Integrative Health , who are about as sympathetic as you can get to this sort of thing “High-quality clinical evidence (i.e., studies in people) to support the use of cinnamon for any medical condition is generally lacking. An analysis of five clinical trials concluded that cinnamon does not appear to affect factors related to diabetes and heart disease.”

Or, for a total failure to do arithmetic, saffron. Stuff says “It is a good source of vitamins, magnesium and iron.” Now, it’s true that saffron is high in nutrients for its weight. A mere 100g of saffron will supply about two-thirds of your daily iron and magnesium, and substantial amounts of vitamins C and B-6. By weight, it does better than spinach. But the typical serving of saffron is a small fraction of a gram, with nutrient contents that would round to zero in any sensible display.

Following the lines of previous StatsChat food advice, I think the photo caption  just needs a bit of editing: “Herbs and spices are an easy way to add healthy elements  flavour to your diet.

(via Mark Hanna and Bart Janssen)

• From Pro Publica, an extended investigation (with detailed simulations) of what will happen to Houston when a big cyclone hits it.  And a “making of” post.

• From 538: A plagiarism scandal in the crossword world: the sort of thing that only computerised searches can really do.

• From Public Address: An example of unfunded drugs other than Keytruda (pembrolizumab) that might be higher up a priority list

• Sensible presentation of stats in a Herald story on seatbelts and crashes

• “Data is a toxic asset” from computer security expert Bruce Schneier

• From Fusion: “How this company tracked 16,000 Iowa caucus-goers via their phones”

• And finally, two notes on the flag referendum. First, if the current flag doesn’t win, New Zealand will go down in history as the new example of opinion-poll failure, since current polls give it an almost 2-1 lead. Second, in case it turns out to be necessary, a mnemonic for the official number of leaflets on the fern: it’s the number of players on a team for the Silver Ferns (netball, 7), plus the White Ferns (cricket, 11), plus the Black Ferns (rugby union, 15) — a celebration of NZ women’s sports.

The Herald Insights section has a multi-day exploration of police burglary reports, starting with a map at the Census meshblock level.

When you have counts of things on a map there’s always an issue of denominators and areas.  There’s the “one cow, one vote” phenomenon where rural areas dominate the map, and also the question of whether to show the raw count, the fraction of the population, or something else.  Burglaries are especially tricky in this context, because the crime location need not be a household, and the perpetrator need not live nearby, so the meshblock population really isn’t the right denominator.  The Herald hasn’t standardised, which I think is a reasonable default.

It’s also an opportunity to link again to Graeme Edgeler’s discussions of  why ‘burglary’ is a wider category than most people realise.

This graph, from the Wall Street Journal last year, was one of a series showing the impact of vaccination

Randall Olson looks at ways to redesign it to communicate the numbers more effectively.

From the Herald today

Coca-Cola would prefer to see more people drinking less of its products rather than a few people drinking a lot. So one can a week is quite alright, according to the folks from Coke.

So, how does that compare to current consumption? We don’t know specifically for Coca-Cola, but Stuff gave figures a year ago for fizzy soft drinks

New Zealanders drank just under 73 litres of carbonated drinks each in 2014 – a fraction lower than Australia where the per-capita consumption sat just under 75 litres.

The figure excludes sports drinks, tea and coffee, and other soft drinks, and 73 litres a year breaks down to nearly four cans a week, and that’s averaged over the whole population. Averaged over just those who drink carbonated soft drinks it’s obviously going to be more.

Coca-Cola Amatil would probably be happy if people who don’t currently drink Coke started drinking a can a week, or if people switched to Coke from L&P, Fanta, or Six Barrel Soda Celery Tonic, but if everyone who drinks fizzy soft drinks regularly were to cut down to one can a week, the market would shrink a lot.