A positive dependence of bubble domain coercive force on inverse film thickness has been attributed to coercivity associated with the film substrate interface [E. B. Moore, B. A. Calhoun, and K. Lee, J. Appl. Phys. 49, 1879 (1978)]. An alternate quantitative explanation is offered that is based on the distribution statistics of ions which possess large single ion magnetic anisotropy. It is shown that the measured coercive force vs film thickness when considered together with magnetic anisotropy provides an estimate of the growth induced order parameter. The order parameters so computed, based on the data reported by Moore, Calhoun, and Lee [ibid.] and Vella‐Coleiroetal. [G. P. Vella‐Coleiro, F. B. Hagedorn, S. L. Blank, and L. C. Luther, J. Appl. Phys. 50, 2176 (1979)] are on the order of 5% which compares favorably with spin resonance measurements performed on Nd3+in YAG [M. D. Sturge, S. L. Blank, and R. Wolfe, Mat. Res. Bull. 7, 989 (1972)]. It seems clear from this analysis that the proposed mechanism could be a major, if not dominant, source for the thickness dependence of coercive force.