Regression Analysis Calculators

Fit a line or curve to data and measure how well it explains the outcome.

8 calculators in this category.

Regression fits an equation to data so that one variable can be described, or predicted, from another. The simplest form is a straight line, and the same idea extends to curves such as quadratic, cubic, and exponential models.

Fitting a model is only the first step. The residuals and the coefficient of determination tell you how well the model describes the data, and predictions outside the range of the observed data should be treated with caution.

Key concepts

Least squares
The standard fitting method. It chooses the line that minimises the sum of the squared vertical distances between the data and the line.
Residual
The difference between an observed value and the value the model predicts.
Coefficient of determination
R², the share of the variation in the outcome that the model accounts for.
Extrapolation
Predicting beyond the range of the data used to fit the model. It is less reliable than predicting inside that range.

Frequently asked questions

What does R-squared tell me?

R-squared is the proportion of the variation in the outcome that the model explains, from 0 to 1. A higher value means a closer fit to the observed data, but it does not show that the model is correct or that predictions will be accurate outside the observed range.