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. Accordingly, the various methods for the determination of a copy number provide the end user with significant information for the evaluation of a copy number of a target genomic sequence; either a gene or genomic sequence of interest.