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More on Bias Corrected Standard Deviation Estimates

November 14, 2018
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More on Bias Corrected Standard Deviation Estimates

This note is just a quick follow-up to our last note on correcting the bias in estimated standard deviations for binomial experiments. For normal deviates there is, of course, a well know scaling correction that returns an unbiased estimate for observed standard deviations. It (from the same source): … provides an example where imposing the … Continue reading More...

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How to de-Bias Standard Deviation Estimates

November 12, 2018
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How to de-Bias Standard Deviation Estimates

This note is about attempting to remove the bias brought in by using sample standard deviation estimates to estimate an unknown true standard deviation of a population. We establish there is a bias, concentrate on why it is not important to remove it for reasonable sized samples, and (despite that) give a very complete bias … Continue reading How...

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R tip: Make Your Results Clear with sigr

November 4, 2018
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R is designed to make working with statistical models fast, succinct, and reliable. For instance building a model is a one-liner: model

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coalesce with wrapr

November 3, 2018
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coalesce is a classic useful SQL operator that picks the first non-NULL value in a sequence of values. We thought we would share a nice version of it for picking non-NA R with convenient operator infix notation wrapr::coalesce(). Here is a short example of it in action: library("wrapr") NA %?% 0 # 0 A … Continue reading coalesce...

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The blocks and rows theory of data shaping

November 1, 2018
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The blocks and rows theory of data shaping

We have our latest note on the theory of data wrangling up here. It discusses the roles of “block records” and “row records” in the cdata data transform tool. With that and the theory of how to design transforms, we think we have a pretty complete description of the system.

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Use Pseudo-Aggregators to Add Safety Checks to Your Data-Wrangling Workflow

October 30, 2018
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One of the concepts we teach in both Practical Data Science with R and in our theory of data shaping is the importance of identifying the roles of columns in your data. For example, to think in terms of multi-row records it helps to identify: Which columns are keys (together identify rows or records). Which … Continue reading Use...

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Conway’s Game of Life in R: Or On the Importance of Vectorizing Your R Code

October 28, 2018
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Conway’s Game of Life in R: Or On the Importance of Vectorizing Your R Code

R is an interpreted programming language with vectorized data structures. This means a single R command can ask for very many arithmetic operations to be performed. This also means R computation can be fast. We will show an example of this using Conway’s Game of Life. Conway’s Game of Life is one of the most … Continue reading Conway’s...

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Designing Transforms for Data Reshaping with cdata

October 25, 2018
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Designing Transforms for Data Reshaping with cdata

Authors: John Mount, and Nina Zumel 2018-10-25 As a followup to our previous post, this post goes a bit deeper into reasoning about data transforms using the cdata package. The cdata packages demonstrates the "coordinatized data" theory and includes an implementation of the "fluid data" methodology for general data re-shaping. cdata adheres to the so-called … Continue reading Designing...

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Quasiquotation in R via bquote()

October 16, 2018
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In August of 2003 Thomas Lumley added bquote() to R 1.8.1. This gave R and R users an explicit Lisp-style quasiquotation capability. bquote() and quasiquotation are actually quite powerful. Professor Thomas Lumley should get, and should continue to receive, a lot of credit and thanks for introducing the concept into R. In fact bquote() is … Continue reading Quasiquotation...

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Piping into ggplot2

October 13, 2018
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Piping into ggplot2

In our wrapr pipe RJournal article we used piping into ggplot2 layers/geoms/items as an example. Being able to use the same pipe operator for data processing steps and for ggplot2 layering is a question that comes up from time to time (for example: Why can’t ggplot2 use %__%?). In fact the primary ggplot2 package author … Continue reading Piping...

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