Methods and systems for determining a physiological parameter in the presence of correlated artifact are provided. One method includes receiving two waveforms corresponding to two different wavelengths of light from a patient. Each of the two waveforms includes a correlated artifact. The method also includes combining the two waveforms to form a plurality of weighted difference waveforms, wherein the plurality of weighted difference waveforms vary from one another by a value of a multiplier. The method further includes identifying one of the weighted difference waveforms from the plurality of weighted difference waveforms using a characteristic of one or more of the plurality of weighted difference waveforms and determining a characteristic of the correlated artifact based at least in part on the identified weighted difference waveform.
