Loess local regression is a nonparametric technique for describing bivariate relationships where the functional form is not known in advance.
Loess Local Regression
Explore with Wolfram|Alpha
References

Referenced on Wolfram|Alpha
Loess Local RegressionCite this as:
Weisstein, Eric W. "Loess Local Regression." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LoessLocalRegression.html