Archive for December 5th, 2014

December 5, 2014

Regression Toward the Mean

madden curse

The Drunkards Walk

Regression toward the mean simply says that, following an extreme random event, the next random event is likely to be less extreme. In no sense does the future event ‘compensate for’ or ‘even out’ the previous event, though this is assumed in the gambler’s fallacy. Regression toward the mean was first described by Victorian polymath Francis Galton. He found that offspring of tall parents tended to be shorter. Also, offspring of shorter parents tended to be taller. Galton stated that processes that did not follow regression towards the mean would quickly go out of control. In finance, the term ‘mean reversion’ has a different meaning. Jeremy Siegel at Wharton uses it to describe a financial time series in which ‘returns can be very unstable in the short run but very stable in the long run,’ in seasonal businesses for example.

The effect can be exploited for general inference and estimation: the hottest place in the country today is more likely to be cooler tomorrow than hotter, as compared to today; the best performing mutual fund over the last three years is more likely to see relative performance decline than improve over the next three years; the most successful Hollywood actor of this year is likely to have less gross than more gross for his or her next movie; the baseball player with the greatest batting average by the All-Star break is more likely to have a lower average than a higher average over the second half of the season, etc.

read more »

December 5, 2014

Body Camera

bodycam by Sam Woolley

Body worn video (BWV), including what is referred to as a body worn camera (BWC), is a video recording system that is typically utilized by law enforcement to record their interactions with the public, gather video evidence at crime scenes, and has been known to increase both officer and citizen accountability. BWCs are notable because their placement, often on the front of a shirt, provides for first person perspective and ultimately a more complete chain of evidence.

Body worn video was first adopted by British police in 2005, appearing in the form of small-scale tests conducted by the Devon and Cornwall Police. In 2006, the first significant deployments of BWV were undertaken as part of the Domestic Violence Enforcement Campaign. The basic command units equipped with the head cameras recorded everything that happened during an incident from the time of arrival which led to the ‘preservation of good-quality first disclosure evidence from the victim.’

read more »