Fit one of our 105 built-in equations, or enter your own. Now including family of growth equations: exponential growth, exponential plateau, Gompertz, logistic, and beta (growth and then decay).

Enter differential or implicit equations.

Enter different equations for different data sets.

Global nonlinear regression – share parameters between data sets.

Robust nonlinear regression.

Automatic outlier identification or elimination.

Compare models using extra sum-of-squares F test or AICc.

Apply constraints.

Differentially weight points by several methods and assess how well your weighting method worked.

Accept automatic initial estimated values or enter your own.

Automatically graph curve over specified range of X values.

Quantify precision of fits with SE or CI of parameters. Confidence intervals can be symmetrical (as is traditional) or asymmetrical (which is more accurate).

Quantify symmetry of imprecision with Hougaard’s skewness.

Plot confidence or prediction bands.

Test normality of residuals.

Runs or replicates test of adequacy of model.

Report the covariance matrix or set of dependencies.

Easily interpolate points from the best fit curve.

Fit straight lines to two data sets and determine the intersection point and both slopes.