SQLServerCentral.com Articles tagged statisticshttp://www.sqlservercentral.com/Articles tagged statistics posted on SQLServerCentral.comen-us360sjones@sqlservercentral.com (Steve Jones)Introduction to StatisticsThis article will give a brief overview of how statistics are generated, stored, and used in SQL Server.]]>http://www.sqlservercentral.com/articles/statistics/162696/Tue, 17 Oct 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/statistics/162696/Statistics in SQL: Student’s t-testMany undergraduates have misunderstood the name 'Students' in the t-test to imply that it was designed as a simple test suitable for students. In fact it was William Sealy Gosset, an Englishman publishing under the pseudonym Student, who developed the t-test and t distribution in 1908, as a way of making confident predictions from small sample sizes of normally-distributed variables. As Gosset's employer was Guinness, the brewer, Phil Factor takes a sober view of calculating it in SQL.]]>http://www.sqlservercentral.com/redirect/articles/163073/Thu, 12 Oct 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/163073/Pattern Recognition via Principal Components AnalysisWe'll look at using principal components analysis to help visualise your data and detect underlying structure or patterns.]]>http://www.sqlservercentral.com/articles/R+Language/159578/Tue, 12 Sep 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/R+Language/159578/Statistics in SQL: The Mann–Whitney U testPhil Factor shows how to use the Mann-Whitney U test in SQL to to find out whether two samples come from the same distribution.]]>http://www.sqlservercentral.com/redirect/articles/161550/Mon, 04 Sep 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/161550/Statistics in SQL: The Kruskal–Wallis TestBefore you report your conclusions about your data, have you checked whether your 'actionable' figures occurred by chance? The Kruskal-Wallis test is a safe way of determining whether samples come from the same population, because it is simple and doesn't rely on a normal distribution in the population. This allows you a measure of confidence that your results are 'significant'. Phil Factor explains how to do it.]]>http://www.sqlservercentral.com/redirect/articles/158174/Thu, 27 Jul 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/158174/Machine Learning for Outlier Detection in RA look into clustering to detect outliers in R. An extension on univariate statistical tests to include multivariate data.]]>http://www.sqlservercentral.com/articles/R+Language/157014/Wed, 05 Jul 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/R+Language/157014/Scoring Outliers in Non-Normal Data with RUsing R to detect outliers is relatively easy, but most methods assume your data is normally distributed. How do you handle skewed datasets?]]>http://www.sqlservercentral.com/articles/Outlier+Detection/156967/Thu, 29 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/Outlier+Detection/156967/Statistics in SQL: Simple Linear RegressionsAlthough linear regressions can get complicated, most jobs involving the plotting of a trendline are easy. Simple Linear Regression is handy for the SQL Programmer in making a prediction of a linear trend and giving a figure for the level probability for the prediction, and what is more, they are easy to do with the aggregation that is built into SQL.]]>http://www.sqlservercentral.com/redirect/articles/156410/Thu, 22 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/156410/Statistics in SQL: Kendall’s Tau rank correlationStatistical calculations in SQL are often perfectly easy to do. SQL was designed to be a natural fit for calculating correlation, regression and variance on large quantities of data. It just isn't always immediately obvious how. In the second of a series of articles, Phil factor shows how calculating a non-parametric correlation via Kendall's Tau or Spearman's Rho can be stress-free.]]>http://www.sqlservercentral.com/redirect/articles/156408/Tue, 20 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/156408/Scoring Outliers with RWhat is normal? More to the point, what is abnormal? We will look at using R to score outliers in a typical monitoring dataset.]]>http://www.sqlservercentral.com/articles/R+Language/156943/Mon, 19 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/R+Language/156943/What is normal? Finding outliers with RHow do you currently set alerting thresholds? What is normal? And more importantly, what is truly abnormal? We will explore these questions.]]>http://www.sqlservercentral.com/articles/R+Language/156935/Tue, 13 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/articles/R+Language/156935/Statistics in SQL: Pearson’s CorrelationSome people will assure you that you can't do any serious statistical calculations in SQL. In the first of a series of articles, Phil factor aims to prove them wrong by explaining how easy it is to calculate Pearson's Product Moment Correlation.]]>http://www.sqlservercentral.com/redirect/articles/156405/Fri, 09 Jun 2017 06:00:00 UThttp://www.sqlservercentral.com/redirect/articles/156405/Can I Use Statistics to Design Indexes?"I’ve noticed that many indexes in my data warehouse aren’t used frequently. Is there a way to use the automatically generated statistics to make useful indexes?"
Kendra Little answers the question in episode 18 of Dear SQL DBA.]]>http://www.sqlservercentral.com/redirect/articles/147560/Tue, 15 Nov 2016 07:00:00 UThttp://www.sqlservercentral.com/redirect/articles/147560/Introduction to Microsoft R Services in SQL Server 2016General introduction to R Services in SQL Server 2016 and how R server works with external stored procedure.]]>http://www.sqlservercentral.com/articles/Microsoft/145393/Thu, 15 Sep 2016 06:00:00 UThttp://www.sqlservercentral.com/articles/Microsoft/145393/