I read some interesting posts on HN that argue the advertising merits of social media. With the Facebook IPO just past us, there has been a bevy of posts and articles on how social media advertising did not work for some particular organization. It isn't only Facebook this time. At least one poster reports disappointing results from Twitter's paid tweets. IIRC, Twitter's advertising platform is still technically in "beta" at this point. In any case, despite the frenzy over social media as the...

I had the excellent opportunity to attend the MacQueenFest a couple of weekends ago in honor of David MacQueen. The venue provided interesting insight into what the alumni of the ML community was up to these days. Many of the slides are now up on the website. The talks were scheduled roughly chronologically based on Dave's contributions. Most were looking forward as much as they were considering the historical significance of the contributions. Read more »

Recently, I finished reading the acclaimed tome by Eric Reis, The Lean Startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses. The ending was the most impressive part to me. Reis is willing to submit his own ideas of innovation accounting and the like to rigorous testing in startup research labs in universities. A footnote mentions that Nathan Furr of BYU and Thomas Eisenmann of Harvard Business School are already studying lean startup...

A couple of papers I spotted a while ago: Easey et al study a measure of order flow toxicity called Volume-Synchronized Probability of Informed Trading in The Microstructure of the ‘Flash Crash’: Flow Toxicity, Liquidity Crashes and the Probability of Informed Trading. Johnson et al considers a large number of mini-flash crashes from 2006 to 2011 in Financial black swans driven by ultrafast machine ecology [PDF].

In this day and age of mobile ubiquity and ever shorter attention spans, it seems that everyone and his uncle are jumping on the mobile app bandwagon. I was doing a little investigating to see how much does it typically cost to build one of these apps. The anecdotal range floating about appears to be in the low tens of thousands. Unsurprisingly, a number of entrepreneurial people have sought to capitalize on this market. Read more »

Wissner-Gross and Freer has a 2010 paper in Physical Review on Relativistic Statistical Arbitrage [official version, pdf]. It makes the observation that as the propagation of prices and trades reach relativistic velocities, that very relativistic limitation of propagation induces some intermediate locations (midpoints between each pair of the 52 world exchanges weighted by turnover velocity) between exchanges from which profitable arbitrage can slow or even stop information propagation. The...

Scala certainly has a lot going for it these days. They have the enthusiasm of at least a couple of the hottest tech companies out there in Twitter and Foursquare. Even Sony is using Scala in some of its systems. There are at least two fairly usable web frameworks, Lift and Play. Akka middleware provides a scalable lock-free concurrency abstraction. XML support is built-in. Interoperability with Java is standard, thus giving Scala access to important systems and APIs such as Hadoop, JSoup,...

The High Scalability blog has a recent post on probabilistic algorithms for approximate counting. The author unfortunately coined the term "linear probabilistic counter", which corresponds to no results if you do a Google search. The more usual terminology is linear counting (a paper from KAIST gives the original definition from 1990) and closely related, approximate counting. The study of probabilistic algorithms is indeed a growing field. It is also tied to that oft forgotten...

A recent post on Scirra claimed that reusing long-lived objects was an ingredient to good JavaScript garbage collection behavior. That made me curious. This claim is generally true when the garbage collector in question is a generational one. Generational garbage collectors split the heap (memory from where all non-stack allocated things are allocated from) into several "generations". The "generational assumption" is that short-lived objects tend to be collected more frequently than long-lived...

Preferred stocks have risen considerably from their lows last year. In fact, PFF (US Preferreds) outperformed the S&P 500 by 130 basis points excluding dividends. Given that the lion's share of the preferreds universe is financial, this isn't too surprising. The flip side of this rise is that preferreds are getting close even not having already exceeded their call price. Of the top 5 holdings in the PFF portfolio, I could find call information for only three of them. The top holding, GM...