COUNTERINTUITIVE PROBLEM, INTUITIVE REPRESENTATION Blog posts about counterintuitive probability problems generate lots of opinions with a high probability. Andrew Gelman and readers have been having a lot of fun with the following probability problem: I have two children. One is a boy born on a Tuesday. What is the probability ... [Read more...]

(This is the first in a series on the use of Graph Algebraic models for Social Science.) Linear Difference models are a hugely important first step in learning Graph Algebraic modeling.  That said, linear difference equations are a completely independent thing from Graph Algebra.  I’ll get into the Graph ... [Read more...]

Having worked with Unix (BSD, HPUX, IRIX, Linux and OSX), Windows (NT4, 2000, XP, Vista and 7) for quite a while I have seen a lot of different software tools. I would like to quickly exhibit my “must have” list. These are the packages that I find to be the single “must ... [Read more...]

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According to internet lore, there's a mathematical equation that governs the lower bound for the socially acceptable age of a potential dating partner: half your age plus 7, or, in mathematical terms, if x is your age then the lower bound is f(x) = x/2 + 7. Seems simple, right? if you're 20, then ... [Read more...]

[This article was first published on Rmetrics blogs, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here) Want to share your [Read more...]

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Matt Asher posted an R experiment on R-bloggers yesterday simulating the random walk which has the property of avoiding zero by quickly switching to a large value as soon as is small. He was then wondering about the “convergence” of the random walk given that it moves very little once ... [Read more...]

Maybe you remember playing this one as a kid. If you are about my age, you may have even created a version of this game as one of your first computer programs. You guess a number, the computer tells you if you if you are too low or high. I’... [Read more...]

  Parent material data is stored within the copm and copmgrp tables. The copm table can be linked to the copmgrp table via the 'copmgrpkey' field, and the copmgrp table can be linked to the component table via the 'cokey' field. The following queries illustrate these table relationships, and show one ... [Read more...]

After finishing the R prototype for data visualization, I've started abstracting the various methods necessary to create beautiful graphs. While there's no preliminary version of the R package yet, I think I've taken a number of exciting steps. These include: Abstracting graph objects. Objects such as lines, scatter plots, and ... [Read more...]

[This article was first published on Rmetrics blogs, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here) Want to share your [Read more...]

Last week I had the opportunity to spend a few days at the Institute for Statistics and Mathematics of the WU Vienna / Wirtschaftsuniversitaet Wien. On Thursday, I gave a seminar on Rcpp and RInside introducing all the recent work with Romain on makin... [Read more...]

Ever wondered which Twitterers you and a friend share? Using R and the twitteR package, there's an easy way to find out. Cornelius Puschmann hacked together some R code to do just that for the Humanities and Technology Camp and it seems to work pretty well. Just replace 'coffee001' ... [Read more...]

I woke up from my afternoon nap feeling a bit off-kilter, so I decided to go for another random walk. In particular, I wanted a journey that avoided the center, but didn’t just run for an exit either. After playing around for a while I came up with this: # ... [Read more...]

Voter targeting for turnout is the process of scoring registered voters using demographic and electoral variables taken from voter lists and commercial databases. The score of all voters together is used to predict overall turnout, which determines the allocation of campaign resources and directs strategy for voter contact and communication. ... [Read more...]

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I've covered a few topics in the past including the plyr package, which is kind of like "GROUP BY" for R, and the merge function for merging datasets. I only recently found the sqldf package for R, and it's already one of the most useful packages I've ever installed. The ... [Read more...]

In World War II, the Allies had a problem: German tanks were often captured, but how many more did the Nazis have in reserve? Allied intelligence estimated around 1400 Panther tanks were being produced a month: a formidable arsenal, and perhaps an insurmountable one given the much smaller numbers being captured ... [Read more...]

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