Sunday, April 27, 2014

10 reasons to switch to ggplot | Mandy Mejia

10 reasons to switch to ggplot | Mandy Mejia: "Making plots is a necessary and useful task for anyone who works with data. While making the standard plots is a pretty straightforward task in most statistical programming languagues, including R, when it comes to using R‘s base graphics to make custom plots (the plots you actually want to make) things can get complicated. As with many of life’s problems, Hadley Wickham comes to the rescue."

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Friday, April 18, 2014

Why UPS Trucks Don't Turn Left

Why UPS Trucks Don't Turn Left: To reduce fuel use and accidents. Confirmed by Myth-busters.

"Mythbusters likely failed to save time on the route by following the rule even more stringently than UPS. While the no left turn rule has an appealingly simple and algorithmic quality to it, you will see UPS drivers take left turns on occasion, especially in residential neighborhoods without much incoming traffic. Asked how often UPS drivers turn right, a driver told ABC:"

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Monday, April 14, 2014

Smart beta

Is ‘smart beta’ the latest magic money tree? - discusses passive investment with a "twist".

"The typical twist is to substitute the standard market capitalisation weighting of an equity index with an alternative weighting, such as dividends or earnings. This is claimed as a smarter approach as market cap indices will inevitably overweight expensive stocks and underweight cheap ones."

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Friday, April 04, 2014

Sampling bias and sampling error

Tim Harford is a discussion of "Big Data" looks at sampling bias and sampling error.

"The Literary Digest, in its quest for a bigger data set, fumbled the question of a biased sample. It mailed out forms to people on a list it had compiled from automobile registrations and telephone directories – a sample that, at least in 1936, was disproportionately prosperous. To compound the problem, Landon supporters turned out to be more likely to mail back their answers. The combination of those two biases was enough to doom The Literary Digest’s poll. For each person George Gallup’s pollsters interviewed, The Literary Digest received 800 responses. All that gave them for their pains was a very precise estimate of the wrong answer."

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Thursday, April 03, 2014

The cost of acquiring information

Streetwise Professor discussed Michael Lewis’s HFT Book: and highlight an application of the Grossman-Stiglitz idea that there will be an equilibrium where the cost of acquiring information will be equal to the benefit of obtaining that information.

 "Moreover, it’s not so clear that order flow information is “non-public”.  No, not everyone has it: HFT has to expend resources to get it, but anybody could in theory do that. Anybody can make the investment necessary to ping a dark pool. Anybody can pay to get a faster data feed that allows them to get information that everyone has access to more quickly. Anybody can pay to get quicker access to the data, either through co-location, or the purchase of a private data feed. There is no theft or misappropriation involved. If firms trade on the basis of such information that can be obtained for a price that not everyone is willing to pay, and that is deemed illegal, how would trading on the basis of what’s on a Bloomberg terminal be any different?"