Study of the Z Boson at LEP

The Z line shape is measured at LEP with an accuracy at the per mille level. Usually it is described in the Standard Model of electroweak interactions with account of quantum corrections. Alternatively, one may attempt different model-independent approaches in order to extract quantities like mass and width of the Z boson. If a fit deviates from that in the standard approach, this may give hints for New Physics contributions. I describe two model-independent approaches and compare their applications to LEP data with the Standard Model approach.