1. A method of identifying a quantitation cycle (C q ) for a PCR amplification reaction without first identifying a threshold fluorescence value, characterized by a plurality of data points each including a cycle value associated with a PCR cycle and a product value associated with a PCR product, the method comprising: a) amplifying one or more target nucleic acid molecules in the PCR amplification reaction; b) hybridizing the amplified target nucleic acid molecules to a plurality of nucleic acid probes to generate one or more fluorescence values; c) measuring the product values for the hybridization of the target nucleic acid molecules to the nucleic acid probes in one or more PCR cycles to generate the plurality of data points associated with the PCR amplification reaction wherein the product values are based on the fluorescence values; d) fitting a plurality of line segments to the data points associated with the PCR amplification reaction; e) identifying a baseline of the PCR amplification reaction; f) identifying a reaction segment associated with an exponential region of the PCR amplification reaction as a first subset of the plurality of line segments having a slope not less than a steepness criteria; g) fitting a reaction line to the data points associated with the reaction segment; and h) extrapolating the reaction line to intersect the baseline at the C q .