[en] Spectral fine structure effects (SFSE) caused by a change in resonance parameters or background cross section on group constant sensitivity coefficients are investigated using a simple model. The investigation is done both differentially - on a resonance by resonance basis, and integrally - for a uniform change in the parameters of all resonances within a group. The numerical results pertain to the ²³⁸U capture group constants in the ZPR - 6/7 critical. It is found that the importance of SFSE strongly depends on the specific resonances, group structure and type of nuclear data variation involved. In many circumstances the effects of SFSE on the group constant sensitivity coefficients are not negligible so it is not justified to neglect them as a general rule. It is recommended that methods capable of routinely taking these SFSE into account for sensitivity and uncertainty analysis applications be developed. Three approaches for doing so are discussed. (Author)