Posts from April 2012 (50)

Team Ratings for Round 8

Here are the team ratings prior to Round 8, 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 56 matches played, 30 of which were correctly predicted, a success rate of 53.57%.

Here are the predictions for last week’s games.

Predictions for Round 8

Here are the predictions for Round 8

Due to no entries being posted in last week’s Stat of the Week competition, there is no winner this week. Make sure you add your nominations in for this week’s competition!

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 April 27 2012.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of April 21-27 2012 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.

The fine print:

• Judging will be conducted by the blog moderator in liaison with staff at the Department of Statistics, The University of Auckland.
• The judges’ decision will be final.
• The judges can decide not to award a prize if they do not believe a suitable statistic has been posted in the preceeding week.
• Only the first nomination of any individual example of a statistic used in the NZ media will qualify for the competition.
• Employees (other than student employees) of the Statistics department at the University of Auckland are not eligible to win.
• The person posting the winning entry will receive a $20 iTunes voucher.
• The blog moderator will contact the winner via their notified email address and advise the details of the $20 iTunes voucher to that same email address.
• The competition will commence Monday 8 August 2011 and continue until cancellation is notified on the blog.

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

According to the Herald, “Baboons learn to tell real words from gibberish”, which would put them ahead of some politicians and academics.   The story describes

… new research that shows baboons are able to pick up the first step in reading – identifying recurring patterns and determining which four-letter combinations are words and which are gobbledygook.

Here’s the press release,  and the scientific paper. After being trained with a bunch of real and made-up words with four letters (no, not the ones you’re thinking of), the baboons could classify new four-letter combinations with about 75% accuracy, compared to 50% for pure chance.

The scientists were a bit more restrained, saying that the baboons were probably looking at which two-letter pairs appeared more frequently in the real words.   In fact, as Mark Liberman describes at Language Log, it was probably even simpler than that.    If the baboons just recognised the shapes of  individual letters, that would be enough for them to get 75% accuracy.  If they were really doing anything more sophisticated they should be doing much, much better than 75% accuracy.

One thing I don’t understand, though, is why French psychologists would try to teach the baboons to recognise English words.

How do we know whether a particular drug, therapy or operation really works, and how well? How reliable is the evidence? Are clinical trials truly unbiased?

Recommended for their plain-language approach to answering these questions are  Testing Treatments: Better research for better healthcare by three doctors and a health advocate, and the University of Sydney’s Smart Choices: Making sense of health advice.

And even better, both are free downloads.

The Herald has a very good story about a breast-cancer genomics project, where researchers looked at mutations in 2000 stored breast-cancer tumour samples, and used these to pigeonhole the tumours into 10 groups.  The hope is that this information can be used, eventually, to work out which tumours respond to which treatments, resulting in more effective treatment with fewer side-effects.

The researchers are properly careful about the implications

“I want to be very cautious here. This is a very important first step, and now what follows is to validate its clinical use,” Caldas said.

Team Ratings for Week 9

Here are the team ratings prior to Week 9, 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 54 matches played, 36 of which were correctly predicted, a success rate of 66.7%.

Here are the predictions for last week’s games.

Predictions for Week 9

Here are the predictions for Week 9. The prediction is my estimated points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

The Dominion Post says “More Kiwis are winning the battle with cancer, with fewer people dying once they are diagnosed.”  Obviously that’s not literally true: the number of deaths per customer is pretty convincingly fixed at one.  What they seem to mean is that people with cancer are surviving longer. This might be true, but the underlying research, unfortunately, doesn’t really show it.

The Otago researchers studied survival time from diagnosis, and showed that it is increasing for many cancers.  That is, Kiwis are spending more time having cancer than they used to.   Survival from diagnosis involves two points.  Moving the time of death later will increase survival, and is a Good Thing, but moving the time of diagnosis earlier without changing the time of death will also increase survival, and doesn’t do anyone much good.

What’s actually happening will be different for different cancers. For example, in breast cancer we know from randomized trials that both phenomena are occuring.  Mammography makes diagnosis happen earlier for everyone, and this results in postponing death for many women.

For solid evidence of improved survival in cancer, you really need to look at something like mortality rates per 100,000 population per year, where there isn’t a problem of moving the goalposts.

It’s often hard to tell who is responsible for a bad statistics story: did the journalist mess up it, or was it already broken? The  Herald’s story “Shoe therapy has real benefits – study” is an exception. It’s the paper’s fault.

If you go to the University of Canterbury home page, there’s a link to their press release about Jessica Boyce’s research.  Ms Boyce has found

• Women who feel more insecure after exposure to media body ideals own more attractiveness-conferring accessories such as shoes and handbags, but not trousers
• Women who are, in general, insecure, own fewer accessories

where ‘women’ means female students at UoC or University of Alberta.   She interprets the first finding to mean that buying accessories is a response to the media images, since the second finding means it isn’t simple reverse causation.  The Herald reports the first of these points, but not the second, which unfortunately makes the interpretation look completely silly, rather than perfectly plausible, though not compelling.

I’m a bit confused as to why UoC is promoting the story  now.  There isn’t any mention made of a publication or conference presentation, and she  still ‘hopes to finish her thesis by the end of the year’, so that’s not the trigger.