# Tag Archives: Correlation

## Anscombe’s Quartet

Here’s an interesting example of why you should never just look at an r value and a regression model without looking at the scatterplot first. Anscombe’s Quartet consists of four data sets. Each has the same sample size and nearly the same mean and standard deviation for the x and y variables, r values, and regression coefficients. But […]

## Pearson Correlation Coefficient (r)

The Pearson Correlation Coefficient (or the Pearson Product Moment Correlation) is the measure of the strength of the linear association between two quantitative variables. The formula is: , where and are the standard scores for x and y that show how many standard deviations x and y are from the mean and n is the […]

## Least-Squares Regression Line

A least-squares regression line is used to assess the relationship between two quantitative variables. It is used to estimate the value of the response variable given an arbitrary value of the explanatory variable. There are four requirements that must be satisfied before a valid least-squares regression line can be calculated: The two variables are quantitative. A […]