Monday, March 28, 2011

GUIs for R

A recent post listed at R Bloggers ( made some erroneous statements about R Commander. Here is a revised description of R Commander with some issues addressed from the earlier blog:
  1. R Commander works on Mac as well in addition to Windows and Linux. The user interface is nicer on Mac than on Windows. The earlier blog omitted R Commander's availability for Mac.
  2. I found installing R Commander to be straightforward as opposed to what was suggested in the above-mentioned blog. If you have R installed on your machine, all you need is a one-liner executed from within R:
    install.packages("Rcmdr", dependencies=TRUE), and R Commander is ready for use.
  3. R Commander has several plug-ins available. On last count, the following Plug-ins were available from
    1. RcmdrPlugin.BCA Rcmdr Plug-In for Business and Customer Analytics RcmdrPlugin.DoE R Commander Plugin for (industrial) Design of Experiments RcmdrPlugin.EHESsampling Tools for sampling in European Health Examination Surveys (EHES) RcmdrPlugin.Export Graphically export output to LaTeX or HTML RcmdrPlugin.FactoMineR Graphical User Interface for FactoMineR RcmdrPlugin.HH Rcmdr support for the HH package RcmdrPlugin.IPSUR An IPSUR Plugin for the R Commander RcmdrPlugin.MAc Meta-Analysis with Correlations (MAc) Rcmdr Plug-in RcmdrPlugin.MAd Meta-Analysis with Mean Differences (MAd) Rcmdr Plug-in RcmdrPlugin.PT Some discrete exponential dispersion models: Poisson-Tweedie RcmdrPlugin.SLC SLC Rcmdr Plug-in RcmdrPlugin.SensoMineR Graphical User Interface for SensoMineR RcmdrPlugin.SurvivalT Rcmdr Survival Plug-In RcmdrPlugin.TeachingDemos Rcmdr Teaching Demos Plug-In RcmdrPlugin.TextMining Rcommander plugin for "tm" package RcmdrPlugin.depthTools R commander Depth Tools Plug-In RcmdrPlugin.doex Rcmdr plugin for Stat 4309 course RcmdrPlugin.epack Rcmdr plugin for time series RcmdrPlugin.orloca orloca Rcmdr Plug-in RcmdrPlugin.qcc Rcmdr qcc Plug-In RcmdrPlugin.qual Rcmdr plugin for quality control course RcmdrPlugin.sos Efficiently search R Help pages RcmdrPlugin.steepness Steepness Rcmdr Plug-in RcmdrPlugin.survival R Commander Plug-in for the survival Package

Thursday, March 24, 2011

Housing pains

imageHousing prices in the United States have collapsed to the level not seen since 2004. While economists and other experts are talking up the economy and are advising consumers that the recession is over, the housing market in the US refuses to rebound in a sustainable fashion.

It suggests that the structural issues underlying the housing price decline have not yet been resolved and thus the housing market continues to falter.

Wednesday, March 23, 2011

Scan all containers, not just the suspicious ones

From The Economist:
Business-school research: No longer all at sea
How to improve shipping-container security

In January, the port of Los Angeles received more than 330,000 TEUs (twenty-foot equivalent units, the standard measuring unit for shipping containers). The possibility that one of those 330,000 containers could have contained a dirty bomb, or worse, keeps security experts up at night. Legislation passed in 2007 requires that every single container entering the United States must be scanned for a potential weapon.
Currently the Customs Bureau receives information on containers’ shipping manifests, which must be transmitted at least 24 hours before departure. If the manifest looks suspicious, the container in question must be taken out of the queue, inspected, and returned to its place. This process can be cumbersome. Stephen Flynn, a Coast Guard veteran and president of the Centre for National Policy, a security-focused Washington think tank, points out that the largest ships begin loading containers 18 hours before departure, making it difficult to find finding the potential offender. Try to handle more than the small fraction of containers which currently get scanned and the whole inspection line becomes, in Mr Flynn’s words, “constipated.”
Just how constipated becomes apparent in modelling done by Nitin Bakshi of London Business School and Noah Gans of Pennsylvania’s Wharton School of Business, who co-authored a recent Management Science paper with Mr Flynn on the question of port security. Using two months’ data from two large international container terminals, Mr Bakshi and Mr Gans created a simulation to gauge what delays would result if the Customs Bureau began requiring that all inbound containers be evaluated. Inspecting only 7% of containers, they found, would mean delays for nearly every single container.
How, then, can the Customs Bureau meet the legal mandate of scanning every container without perpetually snarling ports? Messrs Bakshi, Gans, and Flynn propose an alternative approach. Instead of singling out only those containers whose documentation raises questions, terminal operators would X-ray every container, regardless of its eventual destination. Only those containers flagged during the low-level scan would be subjected to a more thorough search. Think of it as everyone who will be boarding a plane having to go through security, as opposed to a select few being asked to leave their seats and answer questions as the plane was about to depart.
The authors call their approach “industry-centric,” since the terminal operators would play a greater role in the scanning (and bear the corresponding cost). It has several advantages: the entire “dwell time” of a container at the port, not just the last 24 hours, can be used to evaluate its safety. More to the point, subjected to the same simulations as the current inspection process, the industry-centric approach handled all the modelled container traffic with far fewer problems.
The authors intended their paper for two audiences. One are the general shipping and logistics firms. The other is policymakers, who might have given up hope of the possibility of achieving full port scanning. But for them the paper leaves important questions unanswered. How would other countries react to their inbound containers being scanned in an American initiative? For that matter, how would the prospect of scanners in Hong Kong being responsible for scanning goods bound for Los Angeles play politically? Who would control the data resulting from millions of container scans?
This may be why, as Mr Flynn suggests, some political courage would be necessary to change current container security procedures. At least the courageous policymaker will have some research to wave at opponents.

Monday, March 21, 2011

Natural disasters and global supply chains

The New York Times in its Sunday edition carried an excellent article on the impact of Japan's earthquake on global supply chains. Japan is a leading producer of Silicon wafers used in the microchips. With the production of such wafers halted after the earthquake, the IT sector will feel the impact when the existing inventories exhaust in the next few months.

Also, worth noting is the anecdote about a call to a senior HP executive at 3:30 AM about the earthquake and the follow-up meetings of the senior HP execs to plan for the eventualities within hours of the earthquake.

Quake in Japan Broke a Link in Global Supply Chain -