1. A method of determining a classification of amplification data resulting from an amplification of nucleic acid molecules in a sample, the method comprising: receiving, at a computing system, the amplification data, wherein the amplification data is derived from a signal measured from the sample at a plurality of time points, wherein the time points include numbers corresponding to cycles of a reaction of the sample; determining, with the computing system, a quality score of the amplification data, wherein the quality score is a maximum of a group of one or more local quality values (LQVs), wherein an LQV is proportional to a slope of a respective window region containing a plurality of the amplification data points; determining a fractional cycle number (Ct) where a function approximating at least a portion of the amplification data intersects a Ct threshold value; generating, with the computing system, a status classification of the amplification data based on a numerical value of the quality score and based on Ct; determining a quality lower limit function (Qlimit) as a function of cycle number, wherein the Qlimit: is a first constant value for cycle numbers less than a lower cycle number (CtL); decreases from the first constant value to a second constant value, wherein the decrease occurs from CtL to a higher cycle number (CtH); and is the second constant value for cycles higher than the CtH value, wherein generating the status classification includes identifying a distance between a point of {Ct, quality score} and Qlimit.