The random incorporation model as its name suggests proposes that there is no selection at all on which vRNPs are packaged. It is assumed that each vRNP has equal probability of being packaged, and that if enough vRNPS are packaged a particular percentage of budding virions will receive at least one copy of each genome segment. This model is supported by evidence that infectious virions may possess more than eight vRNPs assuring the presence of a full complement of eight vRNPs in a significant percentage of virus particles. Mathematical analysis of packaging suggested that twelve RNA segments would need to be packaged in order to obtain approximately 10% of virus particles that are fully infectious (Enami, 1991), a number that is compatible with experimental data (Donald, 1954). Due to the low amount of RNA per virion (estimated at 1-2% w/w), enumeration of the precise number of RNAs packaged in a virion is difficult.