Blog Archives

Efficient accumulation in R

July 27, 2015
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Efficient accumulation in R

R has a number of very good packages for manipulating and aggregating data (plyr, sqldf, ScaleR, data.table, and more), but when it comes to accumulating results the beginning R user is often at sea. The R execution model is a bit exotic so many R users are very uncertain which methods of accumulating results are … Continue reading Efficient accumulation in R →

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A dynamic programming solution to A/B test design

July 6, 2015
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A dynamic programming solution to A/B test design

Our last article on A/B testing described the scope of the realistic circumstances of A/B testing in practice and gave links to different standard solutions. In this article we will be take an idealized specific situation allowing us to show a particularly beautiful solution to one very special type of A/B test. For this article … Continue reading A dynamic programming solution to A/B test design →

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A bit about Win-Vector LLC

June 26, 2015
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Win-Vector LLC is a consultancy founded in 2007 that specializes in research, algorithms, data-science, and training. (The name is an attempt at a mathematical pun.) Win-Vector LLC can complete your high value project quickly (some examples), and train...

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Why does designing a simple A/B test seem so complicated?

June 22, 2015
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Why does designing a simple A/B test seem so complicated?

Why does planning something as simple as an A/B test always end up feeling so complicated? An A/B test is a very simple controlled experiment where one group is subject to a new treatment (often group “B”) and the other group (often group “A”) is considered a control group. The classic example is attempting to … Continue reading Why does designing a simple A/B test seem so complicated? →

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I do not believe Google invented the term A/B test

June 12, 2015
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The June 4, 2015 Wikipedia entry on A/B Testing claims Google data scientists were the origin of the term “A/B test”: Google data scientists ran their first A/B test at the turn of the millennium to determine the optimum number of results t...

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My favorite R bug

May 23, 2015
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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. ...

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What is new in the vtreat library?

May 7, 2015
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The Win-Vector LLC vtreat library is a library we supply (under a GPL license) for automating the simple domain independent part of variable cleaning an preparation. The idea is you supply (in R) an example general data.frame to vtreat’s designTr...

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I still think you can manufacture an unfair coin

April 13, 2015
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In Gelman and Nolan’s paper “You Can Load a Die, But You Can’t Bias a Coin” The American Statistician, November 2002, Vol. 56, No. 4 it is argued you can’t easily produce a coin that is biased when flipped (and caught). A numb...

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What can be in an R data.frame column?

April 9, 2015
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As an R programmer have you every wondered what can be in a data.frame column? The documentation is a bit vague, help(data.frame) returns some comforting text including: Value A data frame, a matrix-like structure whose columns may be of differing type...

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New video course: Campaign Response Testing

April 8, 2015
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I am proud to announce a new Win-Vector LLC statistics video course: Campaign Response Testing John Mount, Win-Vector LLC This course works through the very specific statistics problem of trying to estimate the unknown true response rates one or more p...

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