Correlated neutron fluctuation experiments have been performed on a poorly coupled, multiple seed-blanket reactor and on a better coupled cylindrical lattice reactor. The fluctuating numbers of counts recorded in various gate times by separated detectors are analyzed in terms of a proposed measure of reactor coupling, the modified coefficient of correlation, MCC, as well as in terms of the conventional dispersion parameter Y. Effects of count losses, statistical bias, and statistical error are examined. Calculations of MCC and Y are carried out in the α-mode form of the product density formalism for a number of detailed reactor models, including several four-energy-group diffusion theory and P-3 transport models for reactor design. Two of these detailed models, incorporating reduced fast-neutron transport and removal cross sections, are in agreement with MCC measurements, while one design model is not.