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Data Science with SQL Server Quick Start Guide

You're reading from   Data Science with SQL Server Quick Start Guide Integrate SQL Server with data science

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Product type Paperback
Published in Aug 2018
Publisher Packt
ISBN-13 9781789537123
Length 206 pages
Edition 1st Edition
Languages
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Author (1):
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Dejan Sarka Dejan Sarka
Author Profile Icon Dejan Sarka
Dejan Sarka
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Table of Contents (10) Chapters Close

Preface 1. Writing Queries with T-SQL FREE CHAPTER 2. Introducing R 3. Getting Familiar with Python 4. Data Overview 5. Data Preparation 6. Intermediate Statistics and Graphs 7. Unsupervised Machine Learning 8. Supervised Machine Learning 9. Other Books You May Enjoy

Measuring dependencies between discrete variables

You can pivot, or cross-tabulate two discrete variables. You measure counts, or absolute frequencies, of each combination of pairs of values of the two variables. You can compare the actual with the expected values in the table. So, what are the expected values? You start with the null hypothesis again—there is no association between the two variables you are examining. For the null hypothesis, you would expect that the distribution of one variable is the same in each class of the other variable, and the same as the overall distribution in the dataset. For example, if you have half married and half single people in the dataset, you expect such a distribution for each level of education. The tables where you show the actual and the expected frequencies are called contingency tables.

Contingency tables show you only visual...

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