Friday, July 20, 2012

Polygraphs and Sex Offenders

Just a short post on the news story that a pilot scheme which administers polygraph tests ('lie detector tests') to sex offenders on probation has been deemed successful, and the Ministry of Justice plans to roll it out nationwide.

The MoJ's research seems reasonable enough: the pilot scheme took place in the Midlands, and comparison groups of offenders were selected from other areas.  The assignment was not randomised, which is unfortunately all too common, but the comparison group was similar to the treatment group on the basis of the most obvious covariates (age, original offence, risk or reoffending, criminal history, etc.).  Based on a quick-ish reading of the paper it seems fairly solid.

Wednesday, July 18, 2012

Reading too much into one number

The BBC points out that deaths from road accidents in the UK increased last year for the first time in 10 years.  In total 1,901 people were killed during 2011, which is 51 more than in 2010.  This is certainly not good.

But is it surprising, in a statistical sense?

Tuesday, July 3, 2012


Is it just me, or is everyone completely unable to explain what a confidence interval is?

The Higgs Boson is back in the news again, here's a Nature News article discussing Cern's latest discovery, which is that
The data contained “a significant excess" of collision events at a mass of around 125 gigaelectronvolts...
 Physicists have maintained that they will not announce the discovery of the Higgs until the signal surpasses 5 sigma, meaning that it has just a 0.00006% chance of being wrong. The ATLAS and CMS experiments are each seeing signals between 4.5 and 5 sigma, just a whisker away from a solid discovery claim.
This is wrong.

Monday, July 2, 2012

Data Overload?

Today I guest blogged about the government's open data plans on the Understanding Uncertainty website.  Check it out here.