A method to operate a ring spinning system containing a ring spinning machine having spinning positions and a winding machine having winding positions. Yarn is spun at the spinning position and wound to a cop. Values of a spinning parameter are determined at different times during the winding of the cop and stored as spinning data. The cop is transported from the spinning position to the winding position, where the yarn is rewound from the cop onto a bobbin. Values of a yarn parameter are determined at at least two different times during the rewinding, and stored as yarn data. The spinning data and the yarn data are assigned to each other such that they relate to the same yarn section. Based on the spinning data and yarn data assigned, an intervention is made on the ring spinning machine.