Method and apparatus for controlling at least one quality feature of a running material web

An apparatus for controlling at least one quality feature of a running fibrous web during its production, the apparatus comprising:

• a measurement system for repeated measurement of the at least one quality feature over an entire width of the fibrous web;
• and
• one of an electronic control and an evaluation unit for determining a variability of the at least one quality feature by way of a variance component analysis dependent on a plurality of profile measured values of a measured value set, said measured value set including several consecutive cross direction (CD) profiles in a machine direction (MD), said measured value set having been recorded during a selectable previous time window, one of said electronic control and said evaluation unit controlling the quality feature intervenes in the production of the fibrous web at an intensity determined by said variance component analysis.