Stats Chat

A couple of years ago, the Herald won Stat of the Week with a story headlined “Goodbye NZ, hello $100,000“. They have fallen for this year’s version of the same survey again, with a story headlined “$100,000 easy for our expats” claiming that more than half of Kiwi expats make over $100000. It should be pretty obvious that this story can’t actually be true, especially given their recurring stories about problems Kiwis face in Australia.

The story comes from a survey by Kea, ‘New Zealand’s Global Network’, of about 30000 of its members, ie, a self-selected, non-representative group making up about 3-5% of Kiwi expats.  Basically, Kea have successfully gotten the paper to report as news their ability to contact and market to a large, high-income set of expats.

Update: For example, at the 2006 Census, average income for Kiwis aged 25-44 working in Australia was just under AU$50,000 (Table 15), about 25% higher than in NZ for the same jobs. It will have gone up a bit since then, but not doubled.

Australia, as you may have noticed, is having an election. Some statistical analysis links

• Pottinger.com
• Simon Jackman (Oz political scientist, at Stanford)
• Adrian Beaumont, at The Conversation
• Daily Kos

The site “WTF Visualizations” does basically what it says on the tin: collecting really badly-inspired data graphics. For example

and

Some of the entries seem too good to be true, a suspicion reinforced by the fact that Google’s reverse image search can’t find them anywhere else on the web, but it is certainly entertaining.

Team Ratings for Round 25

Here are the team ratings prior to Round 25, 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.

Performance So Far

So far there have been 176 matches played, 108 of which were correctly predicted, a success rate of 61.36%.

Here are the predictions for last week’s games.

Predictions for Round 25

Here are the predictions for Round 25. 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.

This is proving to be an extremely unpredictable competition. The Lions absolutely thrashing the Bulls last weekend has resulted in a rankings jump for the Lions and a drop for the Bulls. Certainly the competition is harder to predict than the Australian NRL which in turn is harder to predict than the Super 15.

Team Ratings for Round 4

Here are the team ratings prior to Round 4, 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.

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 9 matches played, 3 of which were correctly predicted, a success rate of 33.3%.

Here are the predictions for last week’s games.

Predictions for Round 4

Here are the predictions for Round 4. 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.

Thank you for your nominations in this week’s Stat of the Week Competition.

We have chosen Andrew Robertson’s nomination of Campbell Live’s GCSB Bill “poll” as the winner:

89% oppose the GCSB bill.

Self-selecting poll made out to be accurate by virtual of the number of people responding. They should have called it a petition, not a poll. A random Research NZ poll, asking a different question, put opposition at 52%.

Comments on this nomination from those members of the Statistics Department included:

“Self-selecting polls are an old favourite but this was a particularly egregious example, if only because of the way various politicians treated the result as being real data.”

And:

“Good use of counter evidence with a properly conducted sample survey.”

And Thomas blogged about this further.

Congratulations Andrew!

There’s an op-ed piece in the New York Times (by a physicist, Adam Frank) about how no-one pays attention to science any more, and it’s all political, with creationism and climate change denial as the main examples.

Chad Orzel (also a physicist) is unconvinced

 [T]he question is whether we’ve fallen off from some golden age when everybody listened raptly to the best science had to offer…. After all, as depressing as it may be for forty-odd percent of the population to want to align themselves with a creationist position (whether from honest belief or out of tribal identification), that’s probably an improvement from the days of the actual Scopes trial. Which, it should be noted, Scopes lost, unlike the several more recent cases where teaching of creationism has been soundly rejected by the courts.

 He points to other questions whether there hasn’t been as much political propaganda and where basic scientific knowledge is improving.

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 August 30 2013.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of August 24 – 30 2013 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.

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From the Journal of Nutritional Science

Young adult males (n 35) were supplemented with either half or two kiwifruit/d for 6 weeks. Profile of Mood States questionnaires were completed at baseline and following the intervention. No effect on overall mood was observed in the half a kiwifruit/d group; however, a 35 % (P = 0·06) trend towards a decrease in total mood disturbance and a 32 % (P = 0·063) trend towards a decrease in depression were observed in the two kiwifruit/d group. Subgroup analysis indicated that participants with higher baseline mood disturbance exhibited a significant 38 % (P = 0·029) decrease in total mood disturbance, as well as a 38 % (P = 0·048) decrease in fatigue, 31 % (P = 0·024) increase in vigour and a 34 % (P = 0·075) trend towards a decrease in depression, following supplementation with two kiwifruit/d. There was no effect of two kiwifruit/d on the mood scores of participants with lower baseline mood disturbance

From the Otago press release

Eating two kiwifruit a day can improve a person’s mood and give them extra energy, new research from the University of Otago, Christchurch (UOC) shows.

Over a six-week period, normally-healthy young men either ate two kiwifruit a day or half a kiwifruit daily as part of a research study into the potential mood-enhancing effects of the fruit.

Researchers found those eating two kiwifruit daily experienced significantly less fatigue and depression than the other group. They also felt they had more energy. These changes appeared to be related to the optimising of vitamin C intake with the two kiwifruit dose

From the Herald

Eating two kiwifruit a day can improve mood and energy levels, a new University of Otago study shows.

Those eating two kiwifruit were found to experience significantly less fatigue and depression than the others. They also felt they had more energy.

I’m not criticizing the research, which was a perfectly reasonable designed experiment, but if the findings are newsworthy, they are also worth presenting accurately.

Two episodes to be noted

First, the GCSB bill.

We’ve had a nomination for Stat of the Week for the Campbell Live bogus poll finding 89% opposition to the bill: you just can’t draw that sort of conclusion from self-selected phone-in polls.  On the other hand, they did get over 50000 identified individuals voting, so as a petition it isn’t completely negligible — that’s a bit more than 1.5% of voters.

The Fairfax/Ipsos real poll found a bare majority who trusted the government to protect privacy and only about 30% who were seriously opposed to the bill.  The pollster or the papers fell down badly by not giving us a party breakdown of these figures.  If half the 30% were National voters, the government should have been concerned, but if, like me, they were mostly Labour/Greens voters already, there isn’t any political problem in ignoring them. It’s also a pity there wasn’t any polling relevant to the most obvious pressure point in the coalition – “Would you vote for ACT if they voted against the bill?” would have been an interesting and important thing to know.

Second, the West Island.

As you may have heard, they are having an election soon. In addition to the traditional election polls there are new automated ‘robopolls’ that are sufficiently cheaper that it’s possible to get a useful sample size in single electorates. Or perhaps not. The Sydney Morning Herald has an interesting report

Lonergan’s own national poll reports only a 2 per cent swing against Labor. Yet in the three seats it polled individually, it found an average swing of 10 per cent. That’s huge, far bigger than we have seen in any Federal election since 1943.