Abstract: A method is described for analyzing a sample for the presence of a nucleic acid wherein the sample is amplified, illustratively using PCR, in the presence of a fluorescent probe capable of detecting the presence of the nucleic acid sample. A baseline region is determined by comparing the fluorescence at various amplification cycles, and the fluorescence at a selected amplification cycle is compared to the baseline region to determine whether the fluorescence measurement falls outside of that baseline region, indicating the presence of the nucleic acid.