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You're reading from  Learning Predictive Analytics with R

Product typeBook
Published inSep 2015
Reading LevelIntermediate
PublisherPackt
ISBN-139781782169352
Edition1st Edition
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Author (1)
Eric Mayor
Eric Mayor
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Eric Mayor

Eric Mayor is a senior researcher and lecturer at the University of Neuchatel, Switzerland. He is an enthusiastic user of open source and proprietary predictive analytics software packages, such as R, Rapidminer, and Weka. He analyzes data on a daily basis and is keen to share his knowledge in a simple way.
Read more about Eric Mayor

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Application – Outlier detection


You might remember that at the beginning of the chapter, we noticed in the stacked bar plot that in our sample of 1,000 roulette spins, the zero was drawn about twice as often as we would expect. We just mentioned it but didn't really have a point of comparison. We now have proportions from 100 samples and thus can examine this a little further. The proportion of zeros can be obtained from the data we have as we simply have to subtract from 1, the sum of proportions of red and black numbers for each of the samples. So let's do this, and add the attribute to the data frame, and get the mean value of this proportion:

samples$isZero = 1-(samples$isRed+samples$isBlack)
Mean = mean(samples$isZero)
Mean

The mean value is 0.0277. We can compute the value we would expect is 1/37, which is 0.0270. The average value of the proportion of zeros in all our 100 samples is therefore almost identical to the expected value. This in no way means that there are no outliers.

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Learning Predictive Analytics with R
Published in: Sep 2015Publisher: PacktISBN-13: 9781782169352

Author (1)

author image
Eric Mayor

Eric Mayor is a senior researcher and lecturer at the University of Neuchatel, Switzerland. He is an enthusiastic user of open source and proprietary predictive analytics software packages, such as R, Rapidminer, and Weka. He analyzes data on a daily basis and is keen to share his knowledge in a simple way.
Read more about Eric Mayor