System and methods for the determination of a copy number of a target genomic sequence; either a target gene or genomic sequence of interest, in a biological sample are described. Various methods utilize a model drawn from a probability density function (PDF) for the assignment of a copy number of a target genomic sequence in a biological sample. Additionally, the methods provide for the determination of a confidence value for a copy number assigned to a sample based on attributes of the sample data. Additionally, various embodiments of an interactive graphical user interface (GUI) may provide an end-user with ready analysis of large sets of data representing a plurality of samples. In various embodiments of an interactive GUI, an end-user may be provided with a synchronized display of tabular and graphical sample data determined by an initial analysis according to a statistical model of a PDF. Such a synchronized display may enable an end-user to readily identify sample data for a subsequent analysis based on user input.