Posts from July 2011 (16)

Professor David Spiegelhalter cites media’s role in dominance of emotions over statistics about travel risks

Journalists urged to ask if “the numbers make sense”

Q: So, have you seen the article about Vitamin D and diabetes?

A: Of course. The tireless staff of StatsChat read even West Island newspapers. It’s a good report, too.

Q: What did the researchers do?

A: They studied 5200 people without diabetes, following them up for five years. 199 of them developed diabetes. The people who ended up with diabetes started off with lower vitamin D levels in their blood.

Q: Where did you get those details?

A: The abstract for the study publication (you can also get the full text there free if you’re at a university or if you wait until next year).

Q: Isn’t it annoying that newspaper websites don’t provide any links to that sort of information?

A: It’s like you’re reading my mind.

Q: One of the study authors is quoted as saying “”It’s hard to underestimate how important this might be.” What do you think?

A: I think he meant “overestimate”.

Q: So, how important is this finding?

A: If it really is an effect of vitamin D, it would be really important.  A simple supplement would be able to dramatically reduce the risk of diabetes.

Q: How can we tell?

A: Someone needs to do a randomized trial, where half the participants get vitamin D and half get a dummy pill. If the effect is real, fewer people getting vitamin D will end up with diabetes.

Q: That sounds like a good idea. Is someone doing a trial?

A: Yes, Professor Peter Ebeling, of the the University of Melbourne.

Q: Is there some useful website where I can find more information about the trial?

A: Indeed.

Q: Will it work?

A: No.

Q: Are you sure?

A: No, that’s why we need the trial.  But it’s a trial of vitamin supplementation, which almost always has disappointing results, and it’s a trial  in adult-onset diabetes, which almost always has disappointing results.

Last week, in Wellington, I saw an ad warning that someone is hurt in a household accident every 48 seconds. Is that a lot?

We need some numbers. The population of NZ is about 4.5 million, and there are about 30 million seconds in a year(*).

Since I’m doing this while trying to avoid traffic in the jaywalking capital of New Zealand, let’s round off the accident rate to one every 50 seconds. That gives 600,000 accidents per year. If we had a population of six million, this would be one accident every ten years, but we only have 4.5 million, so it’s more like one accident per person per seven years.

Somehow, it sounds less impressive that way.

* For real nerds, an even more accurate approximation is π times 10 million seconds.

Stats.org has published an excellent article on the research surrounding risk factors for Sudden Infant Death Syndrome (SIDS), in particular breastfeeding:

Let there be no doubt: not breastfeeding and SIDS are correlated. The problem is that breastfeeding is correlated with many other factors as well, any of which could be the “cause” (or “causes”) behind an increased SIDS rate among people who use formula instead of mothers’ milk. These include a variety of social and cultural differences, differences in care, differences in other feeding patterns, differences in sleeping patterns, differences in genetic makeup, differences in home environment, differences in medical care, etc. The question is whether the evidence points to breastfeeding (or mother’s milk) as a preventative factor by itself and independent of all the other factors with which breastfeeding tends to go hand in hand.

It continues to unravel the statistics and evidence and concludes by saying:

Without the science, the claims of cost due to not breastfeeding – 447 babies and almost 5 billion dollars in economic loss — are like an empty bottle: wanting for real substance.

Read more »

New Zealanders will vote in a referendum in November asking whether they want to change the current voting system used for deciding the makeup of Parliament.

Dr Geoffrey Pritchard and Dr Mark C. Wilson, members of the Centre for Mathematical Social Science at the University of Auckland, have created a simulator intended to voters to compare the 5 proposed electoral systems in a quantitative way, by allowing them to compute quickly, for a given polling scenario, the party seat distribution in Parliament under each system.

You can try it out by going to http://cmss.auckland.ac.nz/2011-referendum-simulator/ and they would appreciate any feedback on how to improve it.

It is written in Javascript and the source code is publicly available. The assumptions made are detailed in the FAQ.

They hope that this will allow a better understanding of the consequences of adopting any of these systems, and complement the qualitative information given by the Electoral Commission.

Explore, share and soon create infographics and data visualisations at the brand new website, Visual.ly

The United Nations Economic Commission for Europe has been releasing a series of guides about communicating with statistics and part 3 is now out:

Communicating with the media (PDF) – a practical tool for producers of statistics find the best way to get their message across and to communicate effectively with the media.

The Making Data Meaningful guides are intended as a practical tool to help managers, statisticians and media relations officers in statistical organisations use text, tables, charts, maps and other devices to bring statistics to life for non-statisticians.

Earlier editions are below:

• Part 1: A guide to writing stories about numbers (PDF)
• Part 2: A guide to presenting statistics (PDF)

The thorough guides are excellent practical primers and the latest one features quite a bit of social media applications.

Thanks to our colleague Peter Davis for pointing out this resource set.

Charlie Park has a great post on Edward Tufte’s “slopegraphs” where he explains what they are, how they’re made, why they haven’t been used too much to date and why they may become more popular very soon.

Great interview on Radio NZ this morning, with Eli Pariser author of ‘The Filter Bubble: What the Internet is Hiding from You’.

Content as well as advertising is now targeted to users. So internet users receive information that reflect their own opinions and interests and as Pariser comments “we don’t see how our experience of the web is different from anyone else’s”. By making our searches personally relevant and individually likeable (“if you like this fact you’ll like that fact”) we don’t get exposed to different perspectives. And we have not had the opportunity to ‘opt out’ of this search personalisation.

Online personalisation started for Google Dec 4 2009. Evidently 57 data points are used including such variables as your past searches, technology and font you use, where you are located, your speed of clicking through. Pariser says, “the watch word in Silicon Valley these days is relevant”.

Mark Zuckerburg of Facebook has been quoted “a squirrel dying in your front yard may be more relevant to you right now than people dying in Africa.” Pariser comments, “I worry about what a web and what a news ecosystem that is built on that idea of relevance might look like”. Presentation by Pariser on this is also here.

The discussion on the benefit of the editorial role in main stream media with the premise of the civic responsibility and ethics, compared to the algorithmic feed of personalised news on the web is interesting food for thought given the current News of the World story.