Method and apparatus for measuring the quality properties of paper and / or board on moving webs of material

Detection of the thickness of a moving web, whereby optical methods are used in a contactless manner and the spectra are evaluated with chemometric methods, is already known per se. According to the invention, an evaluation method consisting of various steps is used. According to said method, various qualities of the paper or cardboard are determined in addition to basic qualities thereof by means of multi-step modeling.