Multi-stage, regression-based PCR analysis system

A method of determining a baseline region for an amplification curve resulting from an amplification process of a biological and/or chemical reaction, the method comprising:

• receiving a set of data points representing a curve having a baseline portion and a growth portion, each data point representing a physical quantity of a substance during an amplification process;
• determining, with a processor, a function that approximates the set of data points;
• calculating a first derivative of the function to obtain a first derivative function;
• determining, with the processor, an end of a baseline region by:
• for each of a plurality of points:
• integrating the first derivative function from the respective point to a fixed location of the first derivative function to obtain a respective integrated area;
• and
• selecting a point whose integrated area is within a specified range as the end of the baseline region;
• and
• determining a beginning of the baseline region.

A method of determining a reference value of a biological and/or chemical reaction from a data set representing an amplification process of the reaction, the method comprising:

• receiving a set of data points representing a curve having a baseline portion and a growth portion, each data point representing a physical quantity of a substance during an amplification process;
• determining, with a processor, a function that approximates the set of data points;
• calculating, with the processor, at least two different derivatives of the function;
• identifying a respective time in the amplification process where each derivative has a maximum value, the respective times for the different derivatives being different;
• calculating, with the processor the reference value of the biological and/or chemical reaction as a weighted average of the respective times.