# Monthly Archives: April 2011

## Day #30-31 errorbars here, errorbars there

April 28, 2011
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Today I have been playing with the errorbars from knime. To recreate the plot from http://flyordie.sin.khk.be/2011/04/20/day-27-a-lot-of-graphics-in-one-place/ I had to be able to create 2 y-axis, and multiple plots on 1 graph. At the end of the day I ...

## Job Search Part 5: It’s Policy Time!

April 27, 2011
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This is the last post of this special mini-series on the job search and matching theory of unemployment. I will probably be extremely distracted for the next few months, including a month-long vacation in Europe to shake the horrors of undergrad off me...

## “Inside” Functors — Multiple Arguments

April 27, 2011
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Again for HTML reasons this has been taken to http://strugglingthroughproblems.blogspot.com/2011/04/inside-functors-multiple-arguments.html

## A test of Ledoit-Wolf versus a factor model

April 27, 2011
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Statistical factor models and Ledoit-Wolf shrinkage are competing methods for estimating variance matrices of returns.  So which is better?  This adds a data point for answering that question. Previously There are past blog posts on: the idea of variance matrices factor models of variance The data in this post are from the blog posts: “Weight … Continue reading...

## How to make 3-D graphics from SAS data

April 27, 2011
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The blog SAS Analysis shows how to create 3-D images from SAS data ... using R: Some SAS programmers like to use SAS/IML to call R’s functions . However, it seems that SAS/IML fails to work with the latest versions of R since 2.12 . Others tend to play tricks to call R into SAS’s data step...

## DST is a b!tch, be careful with POSIX in a stupid timezone

April 27, 2011
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At the department we have been analyzing some transaction data for some time. We got a new dataset with lots of transactions. Once you need interpurchase (IPT) times, posix is quite useful, as you can easily difference transactions to generate IPTs.So ...

## VideoLectures.net Recommender System Competition

April 27, 2011
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A Guest post to R-bloggers by Bart Blaszczyk. * * * * * * * * This week a new data competition for the best recommendation system begins. Similar in a form to the famous Netflix Prize, asks data scientists, algorithm geeks and statisticians to devise the most accurate algorithm that suggests in personalized way what movies may be of interest for visitors...

## Day #28 ggplot2 in knime

April 27, 2011
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If you haven’t read yesterday’s post, I advise you to do so, because this is the fix of yesterday. Day #27: A lot of graphics in one place I found out how to use ggplot2 in knime. Say, for example, your code is this: library(ggplot2) myplot...

## Day #30-31 errorbars here, errorbars there

April 27, 2011
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Today I have been playing with the errorbars from knime. To recreate the plot from http://flyordie.sin.khk.be/2011/04/20/day-27-a-lot-of-graphics-in-one-place/ I had to be able to create 2 y-axis, and multiple plots on 1 graph. At the end of the day I ...

## Choosing a Machine Learning Classifier

April 26, 2011
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How do you know what machine learning algorithm to choose for your classification problem? Of course, if you really care about accuracy, your best bet is to test out a couple different ones (making sure to try different parameters within each algorithm as well), and select the best one by cross-validation. But if you’re simply looking for a “good...