Monthly Archives: May 2015

Geomorph update 2.1.5 Now Available!

May 24, 2015
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Geomorph update 2.1.5 Now Available!

Geomorph users,We have uploaded version 2.1.5 of geomorph* to CRAN. The windows and mac binaries have been compiled and the tarball is available.New Features:New Auto Mode allows users to include pre-digitized landmarks added to build.te...

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another viral math puzzle

May 24, 2015
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another viral math puzzle

After the Singapore Maths Olympiad birthday problem that went viral, here is a Vietnamese primary school puzzle that made the frontline in The Guardian. The question is: Fill the empty slots with all integers from 1 to 9 for the equality to hold. In other words, find a,b,c,d,e,f,g,h,i such that a+13xb:c+d+12xe–f-11+gxh:i-10=66. With presumably the operation

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Review of ‘Advanced R’ by Hadley Wickham

May 24, 2015
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Review of ‘Advanced R’ by Hadley Wickham

Executive summary Surprisingly good. And it’s not like my expectations were especially low. Structure There are 20 chapters.  I mostly like the chapters and their order. Hadley breaks the 20 chapters into 4 parts.  He’s wrong.  Figure 1 illustrates the correct way to formulate parts. Figure 1: Chapters and Parts of Advanced R.    Introductory R There The post Review of...

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My favorite R bug

May 23, 2015
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My favorite R bug

In this note am going to recount “my favorite R bug.” It isn’t a bug in R. It is a bug in some code I wrote in R. I call it my favorite bug, as it is easy to commit and (thanks to R’s overly helpful nature) takes longer than it should to find. The … Continue reading My...

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Parametric Inference: Likelihood Ratio Test Problem 2

May 23, 2015
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Parametric Inference: Likelihood Ratio Test Problem 2

More on Likelihood Ratio Test, the following problem is originally from Casella and Berger (2001), exercise 8.12.ProblemFor samples of size $n=1,4,16,64,100$ from a normal population with mean $mu$ and known variance $sigma^2$, plot the power function of the following LRTs (Likelihood Ratio Tests). Take $alpha = .05$. $H_0:muleq 0$ versus $H_1:mu__0$$H_0:mu=0$ versus $H_1:muneq 0$SolutionThe LRT statistic is given by...

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My New Book and Other Matters

May 22, 2015
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My New Book and Other Matters

I haven’t posted for a while, so here are some news items: My new book, Parallel Computation for Data Science, will be out in June or July. I believe it will be useful to anyone doing computationally intensive work. After a few months being busy with the book and other things, I have returned to … Continue reading My...

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Simulation-based power analysis using proportional odds logistic regression

May 22, 2015
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Simulation-based power analysis using proportional odds logistic regression

Consider planning a clinicial trial where patients are randomized in permuted blocks of size four to either a 'control' or 'treatment' group. The outcome is measured on an 11-point ordinal scale (e.g., the numerical rating scale for pain). It may be reasonable to evaluate the results of this trial using a proportional odds cumulative logit

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visNetwork, Currencies, and Minimum Spanning Trees

May 22, 2015
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Just because I’m ignorant doesn’t mean I won’t try things.  Feel free to correct any ignorance that follows.  More than anything I would like to feature the new htmlwidget visNetwork.  I thought  the example from Minimum Spanning Trees in R a...

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R Now Contains 150 Times as Many Commands as SAS

May 22, 2015
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R Now Contains 150 Times as Many Commands as SAS

by Bob Muenchen In my ongoing quest to analyze the world of analytics, I’ve updated the Growth in Capability section of The Popularity of Data Analysis Software. To save you the trouble of foraging through that tome, I’ve pasted it below. … Continue reading →

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Old is New: XML and rvest

May 22, 2015
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Huh… I didn’t realize just how similar rvest was to XML until I did a bit of digging. After my wonderful experience using dplyr and tidyr recently, I decided to revisit some of my old RUNNING code and see if it could use an upgrade by swapping out the XML dependency with rvest. Ultra Signup: Treasure Trove of Ultra Data If you’re...

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