Data Science: Correlation (Definitions)

[correlation coefficient:] "A measure to determine how closely a scatterplot of two continuous variables falls on a straight line." (Glenn J Myatt, "Making Sense of Data: A Practical Guide to Exploratory Data Analysis and Data Mining", 2006)

"A metric that measures the linear relationship between two process variables. Correlation describes the X and Y relationship with a single number (the Pearson’s Correlation Coefficient (r)), whereas regression summarizes the relationship with a line - the regression line." (Lynne Hambleton, "Treasure Chest of Six Sigma Growth Methods, Tools, and Best Practices", 2007)

[correlation coefficient:] "A measure of the degree of correlation between the two variables. The range of values it takes is between −1 and +1. A negative value of r indicates an inverse relationship. A positive value of r indicates a direct relationship. A zero value of r indicates that the two variables are independent of each other. The closer r is to +1 and −1, the stronger the relationship between the two variables." (Jae K Shim & Joel G Siegel, "Budgeting Basics and Beyond", 2008)

"The degree of relationship between business and economic variables such as cost and volume. Correlation analysis evaluates cause/effect relationships. It looks consistently at how the value of one variable changes when the value of the other is changed. A prediction can be made based on the relationship uncovered. An example is the effect of advertising on sales. A degree of correlation is measured statistically by the coefficient of determination (R-squared)." (Jae K Shim & Joel G Siegel, "Budgeting Basics and Beyond", 2008)

"A figure quantifying the correlation between risk events. This number is between negative one and positive one." (Annetta Cortez & Bob Yehling, "The Complete Idiot's Guide® To Risk Management", 2010)

"A mechanism used to associate messages with the correct workflow service instance. Correlation is also used to associate multiple messaging activities with each other within a workflow." (Bruce Bukovics, "Pro WF: Windows Workflow in .NET 4", 2010)

"Correlation is sometimes used informally to mean a statistical association between two variables, or perhaps the strength of such an association. Technically, the correlation can be interpreted as the degree to which a linear relationship between the variables exists (i.e., each variable is a linear function of the other) as measured by the correlation coefficient." (Herbert I Weisberg, "Bias and Causation: Models and Judgment for Valid Comparisons", 2010)

"The degree of relationship between two variables; in risk management, specifically the degree of relationship between potential risks." (Annetta Cortez & Bob Yehling, "The Complete Idiot's Guide® To Risk Management", 2010)

"A predictive relationship between two factors, such that when one factor changes, you can predict the nature, direction and/or amount of change in the other factor. Not necessarily a cause-and-effect relationship." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"Organizing and recognizing one related event threat out of several reported, but previously distinct, events." (Mark Rhodes-Ousley, "Information Security: The Complete Reference" 2nd Ed., 2013)

"Association in the values of two or more variables." (Meta S Brown, "Data Mining For Dummies", 2014)

[correlation coefficient:] "A statistic that quantifies the degree of association between two or more variables. There are many kinds of correlation coefficients, depending on the type of data and relationship predicted." (K  N Krishnaswamy et al, "Management Research Methodology: Integration of Principles, Methods and Techniques", 2016)

"The degree of association between two or more variables." (K  N Krishnaswamy et al, "Management Research Methodology: Integration of Principles, Methods and Techniques", 2016)

"A statistical measure that indicates the extent to which two variables are related. A positive correlation indicates that, as one variable increases, the other increases as well. For a negative correlation, as one variable increases, the other decreases." (Jonathan Ferrar et al, "The Power of People: Learn How Successful Organizations Use Workforce Analytics To Improve Business Performance", 2017)