Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and here for more.


The term "residual" defines the fraction of variability which cannot be explained by a given model. Residuals should be inspected carefully when establishing models, since they give valuable hints on the fulfillment of model assumptions.

Residuals are calculated by subtracting the model estimates from the actual data. The figure below shows the model and the data on the left, and the residuals on the right.