# Monthly Archives: May 2010

## Tuesday’s child is full of probability puzzles

May 28, 2010
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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 I have two boys? The

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## Dynamic Modeling 1: Linear Difference Equations

May 28, 2010
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(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 algebra stuff in the next post or

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## Must Have Software

May 28, 2010
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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 have offerings” in Related posts:

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## Creating surface plots

May 28, 2010
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A 3d wireframe plot is a type of graph that is used to display a surface – geographic data is an example of where this type of graph would be used or it could be used to display a fitted model with more than one explanatory variable. These plots are related to contour plots which

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## Because it’s Friday: The dating equation

May 28, 2010
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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 the minimum socially acceptable age...

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## Follow Rmetrics on Twitter

May 28, 2010
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(This article was first published on Rmetrics blogs, and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on their blog: Rmetrics blogs. R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave,...

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## Rmetrics 2010

May 28, 2010
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The 4th User/Developer Meeting on computational Finance and Financial Engineering (Rmetrics 2010) will take place once again in Meielisalp. This is the first time I'll attend the conference, but I'm not coming empty handed. I'll present the wo...

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## A repulsive random walk

May 28, 2010
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$A repulsive random walk$

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 is large enough. The values

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## The guessing game in R (with a twist, of course)

May 27, 2010
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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’ve limited the number of maximum

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## Getting Parent Material Data out of SSURGO

May 27, 2010
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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 possible strategy for extracting the parent material information...

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