Stats Chat

Well, for the past two days, we’ve been listening to our MSc and BSc(Hons) students presenting the results of their research projects.  Here’s a list of titles:

Applying Propensity Scores to Compare Hospital Performance

Order book modelling on the New York Stock Exchange

What Foods are Safe to Eat?

In a Genetic Haystack: Exploring Sparse Microarray Time-Series

Network Meta-Analysis: A Simulation Study and Update

Genome-wide Heterozygosity and Successful Aging in the Cardiovascular Health Study Cohort

Dynamic Advertising Modelling by Implementing Bayesian Forecasting

Occupation-based Socioeconomic Scores: A Path Analysis Approach

Dotcharts in R – What, Whoa and Why

Simulation and Estimation of Stochastic Differential Equations

In or Out? Examining Whether Macroeconomic Variables Help Predict the NZ/US Exchange Rate

Bayesian Estimation of Variance in the Binomial Option Pricing Model

The Introductory Statistics Course: Student Attitudes and Perceived Relevancy

Using Principal Components for the Evaluation Likelihood Ratios for Forensic Trace Evidence

Assessing Genetic Relatedness for Invasive Rats

Hospital Restructuring: was it Harming Us?

Reproducible Research – The Report with Nothing to Hide

Choosing a Transformation or Distance Measure in Ecology: What Do You Throw Away?

Multivariate Extension of ATRIMS Using Copulas with an Application to the Stochastic Volatility Model

A Comparison of Lenth’s Method and APC for the Analysis of Unreplicated Experiments

Constructing Confidence Regions for the Stationary Points of Second Order Response Surfaces

Stepped Wedge Randomised Controlled Trial Design: A Systematic Review and a Case Study

Discrete Choice Modelling with VGAM

Today, the department is running an all-day workshop for high-school teachers.

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 November 25 2011.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of November 19-25 2011 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.

Over-protective mothers are now being blamed for road deaths among teenage boys.  I suppose it’s a change from saying that overprotective mothers make boys gay, as Freud famously imagined.

We’ve written before about the problem of seeing and trying to explain a trend when there’s really nothing there but random variation.  That isn’t what’s happening here.  In this case the trend is real. It’s just in the opposite direction to the explanation. (more…)

Goodhart’s Law says Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes.

The Big Mac Index has been used to compare prices across countries, as we have noted before.  Brazil Argentina currently has very high prices due to a combination of inflation and a strong economy, and this shows up glaringly in the Big Mac Index.

Tyler Cowen reports (translating a Spanish original) that the Brazilian Argentinian government has persuaded McDonalds to lower the price of the Big Mac (relative  to other McDonalds items, and relative to competing hamburgers), so that Brazil’s Big Mac Index becomes more competitive.

Updated: I actually do know that Argentina and Brazil are different countries, and that Brazil doesn’t speak Spanish.

Housing prices are in the news again, and I was curious to see how much of the change in prices is just ordinary inflation, and how much is real improvement. Over the past 45 years, housing prices have increased more than fifty-fold.  Barfoot & Thompson like to point this out, and they have a graph of Auckland prices that is designed to show the increase very dramatically.  But other things from apples to yachts are also more expensive than they were in the past. (more…)

Thanks for to those who nominated something for last week’s Stat of the Week competition, however no winner is being awarded this week.

We would like to pay special tribute to Stephen Cope’s excellent graphic on the Rena – not only because it improved a terrible one in the NZ Herald but because his was so clear. Thanks Stephen!

If you see a poor graphic in the media and have suggestions for how it can be improved, please let us know!

Everyone has heard of the placebo effect, but a lesser known effect is its counterpart, the so-called nocebo effect, which Wikipedia describes as:

A harmful, unpleasant, or undesirable effects a subject manifests after receiving an inert dummy drug or placebo. Nocebo responses are not chemically generated and are due only to the subject’s pessimistic belief and expectation that the inert drug will produce negative consequences.

In today’s Guardian paper, they’ve printed an edited version of Penny Sarchet’s winning essay on nocebo research in the Wellcome Trust science writing competition. Well worth a read.

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 November 18 2011.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of November 12-18 2011 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.

Q: Did you see the BBC news article about dietary fibre and bowel cancer?

A: No, but I’ll go look. [reading noises]

Q: Well?

A: They definitely  get points for linking to the article in the British Medical Journal (and it’s even an open access article that anyone can read).

Q: Haven’t we beaten that issue into the ground yet?

A: Apparently not. (more…)

Stuff is reporting, in their Oddstuff section, a story about twins who will turn 11 tomorrow, 11-11-11.  How odd is this?

There are about 64000 births per year in New Zealand, or about 175 per day.  The rate of twin births is somewhere between 1 in 60 and 1 in 100, so on an average day, such as 11-11-00, there will be about two pairs of twins born.  So we’d expect two pairs of Kiwi twins to turn 11 on 11-11-11. You might wonder what the other pair was doing.

If you read the story, though, you see it’s actually from the United States: Madison, Wisconsin.  There were more than 50,000 pairs of  twins born in the US in 2000, so we’d expect about 136 pairs turning 11 tomorrow.

There must be lots of community papers across the world reporting on a pair of local twins turning 11 tomorrow.  The interesting question  is how the Overman twins got their story on to the Associated Press wire and into 181 (and counting) newspapers around the world, and how the same mechanisms are used on stories that aren’t just harmless fluff.

Updated:  Now there’s a local pair of twins, one of  whom is quoted as saying “There are probably only one or two [sets of twins] in the world turning 11 on that date.” 

Updated again: You’d expect there to be several sets of birthday triplets out there somewhere in the industrialized world, and one set have shown up in Windsor (Canada). Unfortunately, the story also spends a lot of time with Uri Geller, trying to get Deep Significance out of the date.