Posts filed under General (3156)

Even so often, one of the NZ lottery jackpots gets to be unusually large and we see an increasing stream of search engine hits from people looking for ways to win.

Via @mapcaptenor, here’s an analysis of the USA’s Powerball lottery, with the conclusion

The one sentence takeaway: no matter how big the jackpot gets, you should only buy Powerball tickets for their entertainment value.

In fact, an economics argument can get you this conclusion much more easily. All the facts you have about the lottery are available to pretty much anyone in the country, as is the opportunity to buy tickets. Unless you think you are one of the top handful of smartest investors in New Zealand, you should assume that other people will draw the same conclusion as you about whether it’s worth buying tickets. If you think it’s worth buying, so will quite a lot of other people, and collectively you’ll buy up enough tickets to ensure that the expected benefit falls to nearly zero.

The Herald, like many other news sources worldwide, has picked up on a paper in the Proceedings of the National Academy of Sciences. Like the other glamorous top science journals, PNAS publishes some top-level science, and also some that is perhaps not quite up to the standard.

The story says that men with smaller testicles make better fathers, based on a fairly weak correlation in a relatively small sample of new fathers. As Dr Isis points out, this sample only included 9 dads who did more childcare than the mothers.

If you look at the paper (which you can’t, unless you have a subscription), you find that there was a moderately strong relationship between testosterone levels in the blood and the ‘parenting quality’ questionnaire. When the researchers compared men with similar levels of testosterone and similar working hours, there was no correlation between testicle size and parenting, but if testosterone and hours at work were ignored there was fairly weak evidence of a correlation between testicle size and parenting.  (The researchers presented their evidence using p-values, with p=0.08 , not up to usual standards. I think it would be unconvincing with other ways of measuring evidence as well)

The Discussion section of the paper starts out

which is, apparently unintentionally,  a pretty damning criticism.

Oh, the post title? Anyone old and British should be able to explain it

Statistics New Zealand is marking 120 years of women’s suffrage with a nice little infograph (click to enlarge).

The graphics are a recent development, and long may they continue (and that the print media and teachers make the most of them). The last SNZ graphic I saw marked the birth of a certain baby called George, and looked at a range of facts and figures to do with child-rearing in New Zealand.

If you’re in Palmerston Nth, next Tuesday 17th, James Curran is talking as part of the Royal Society’s 10×10 series of maths presentations around the country

Advances in science have allowed forensic practitioners to recover and quantify evidence from crime scenes in more ways than ever before. As a consequence, judges, lawyers, and juries struggle to decide or understand what the value of scientific evidence might be, and how it impacts on the case at hand. This talk will look at how statistics is being used to aid in the legal process.

And if you’re in Auckland on October 1, I’m presenting at Nerdnite again, (6:30 for 7pm, Nectar bar, above the Kingslander)

“The game of rock, paper, scissors was known in Asia millennia ago. At about the time of Captain Cook, a French political scientist discovered that it isn’t always possible to construct an ordering by considering things two at a time.  In the 1970s a statistician showed how to cheat at dice using this idea. The implications for experiments with a treatment group and a control group are still underappreciated.”

I have now been able to assemble the data for predicting the ITM Cup. The success figures stated below are what would have been achieved had I started predicting in Round 1. The parameters for this season’s predictions were chosen without considering any results from this year and the method is purely algorithmic once the parameters have been chosen.

Team Ratings for Round 5

Here are the team ratings prior to Round 5, 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 30 matches played, 24 of which were correctly predicted, a success rate of 80%.

Here are the predictions for last week’s games.

Predictions for Round 5

Here are the predictions for Round 5. 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 6

Here are the team ratings prior to Round 6, 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 15 matches played, 7 of which were correctly predicted, a success rate of 46.7%.

Here are the predictions for last week’s games.

Predictions for Round 6

Here are the predictions for Round 6. 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 Finals Week 1

Here are the team ratings prior to this week’s games, 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 192 matches played, 116 of which were correctly predicted, a success rate of 60.42%.

Here are the predictions for last week’s games.

Predictions for Finals Week 1

Here are the predictions for Finals Week 1. 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.

I missed this when it came out in early August. Alan Schwarz, of the New York Times, has won this year’s award for excellence in statistical reporting, from the American Statistical Association.

He’s probably best known for his reporting on concussion and brain injury in footballers, which was a finalist for the Pulitzer Prize in 2011. Similar issues are now being raised in rugby.

From the Herald (and originally the Daily Mail)

People who bottle up their feelings are at least a third more likely to die young than those who regularly express what they’re thinking.

Not what the study says — there is a hazard ratio of 1.35 but even the researchers only claim this is a 3 year reduction in life expectancy and they don’t say anything about how likely people are to die young.

But when the researchers looked at specific causes of death they discovered that the risks increased by 47 per cent for heart disease and 70 per cent for cancer.

This was a fairly small study, with only 34 heart disease deaths and 37 cancer deaths, and the authors make it pretty clear the evidence for heart disease was too weak even for them to be comfortable — they say

Findings for CVD death were in a direction and of a magnitude consistent with prior work though they did not reach statistical significance.

How do I know all this? Well the story doesn’t give the names of any of the researchers, let alone link, but it does give the journal name and it turns out the paper appeared only a month ago, so it didn’t take too much work.

Assuming the correlation is real, it could still easily be due to other factors.  The researchers deliberately didn’t attempt any control for health risks, in case these were due to emotion suppression. For example, they didn’t distinguish smokers and non-smokers, because of the concern that smoking might be due to emotion suppression.  They didn’t even ask if people already had a cancer diagnosis at the start of the study.

The story does quote an independent expert. Well, sort of.

London-based business psychologist Voula Grand said: “It has long been thought that cancers are partly the result of suppressed emotions.

Judging from their web sites about cancer prevention, neither the American Cancer Society nor Cancer Research UK seems to know about this. They might be more reliable than the Daily Mail.

Wednesday, Sept 4, NZ Herald, lead

Latest Auckland house price stats show a largely flat property market over the past five months and one economist says we may have seen the first sign of regional price pressure easing.

Monday, Sept 9, NZ Herald, lead

Rising New Zealand property values accelerated last month as the lack of listings in Canterbury and Auckland continue to overheat the market,