Blog Archives

A Shiny App for Playing with OLS

November 11, 2013
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A Shiny App for Playing with OLS

Ordinary least squares continues to be the staple estimator for causal inference for good reason.  In order to help new and veteran OLS users get a better sense of how it is working I have created a shiny app that allows for instant interactivity ...

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The Motivation for the Poisson Distribution

November 4, 2013
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# The Poisson distribution has the interesting property that it# models outcomes from events that are independent and equally# likely to occur. The distribution takes only one parameter mu# which is equal to both the mean (expected number of events) #...

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Consumer’s Choosing an Optimal Bundle – Utility Maximization

November 2, 2013
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Consumer’s Choosing an Optimal Bundle – Utility Maximization

# The theoretical basis of classical consumer theory lies# in utility maximization. The idea is that consumers# make consumption decisions based on choosing a bundle # of goods that will maximize individual utility.# Despite this hypothesis being large...

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Efficiency Balanced Information Criterion for Item Selection

November 1, 2013
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Efficiency Balanced Information Criterion for Item Selection

# Han (2012) in the paper "An Efficiency Balanced Information Criterion # for Item Selection in Computerized Adaptive Testing" proposes a method# of evaluating potential items based on expected item potential information # as a function of maximum pote...

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A Call for Contributors

October 29, 2013
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Dear Readers,This blog has been going for a year and a half now and I have posted nearly 300 posts to date.  I plan to continue to post though I am going to probably continue to shift my focus from daily blogging to that of getting a dissertation ...

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Modified Bin and Union Method for Item Pool Design

October 28, 2013
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Modified Bin and Union Method for Item Pool Design

# Reckase (2003) proposes a method for designing an item pool for a computer# adaptive test that has been known as the bin and union method. This method# involves drawing a subject from a distribution of abilities. Then selecting# the item that maximi...

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Maximum Likelihood Estimation and the Origin of Life

September 8, 2013
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Maximum Likelihood Estimation and the Origin of Life

# Maximum likelihood Estimation (MLE) is a powerful tool in econometrics which allows for the consistent and asymptotically efficient estimation of parameters given a correct identification (in terms of distribution) of the random variable. # It i...

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ThinkNum – A new interactive public database and graphing tool!

September 5, 2013
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ThinkNum – A new interactive public database and graphing tool!

Thinknum.com is a new free data service similar to Quandl.com in that they organize and list publicly available data sets.  Currently they are using data from 2,000 data sources which sounds good compared with Quandl's 400+ source.  Overall, ...

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Making regex examples work for you!

August 30, 2013
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One of the most frequently used string recognition algorithms out there is regex and R implements regex.  However, users can often be frustrated with how despite taking examples verbatim from many sources such as stackoverflow they do not seem to ...

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Doodling in R!

August 21, 2013
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Doodling in R!

# I am working on creating some functions that will be capable of creating shapes and plots that look hand drawn. # I have made some progress in this goal. # In that process I have also discovered that I can make some doodles that look hand d...

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