Abstract
A contact number was introduced by Akao in order to evaluate the degree of mixing. The contact number can be defined as the number of particles which are in contact with a particular particle, so-called a “specified particle.” This specification, however, brings a restriction into the sampling. That is, sampling carried out n times cannot always yield n samples.
A new definition of the contact number is presented, and its distribution is derived from the conventional ones with specified particles. The estimation precision of the new contact number is compared to that of the conventional one. The new contact number is found to be preferable for almost all even concentrations.
