A method to effectively compare electron-capture rates calculated from both theoretical and experimental Gamow-Teller strength distributions has been created. In this thesis, the method has been outlined and applied to the transition from 56Fe to 56Mn. Factors that significantly impact the electron-capture rates are the stellar temperature, the stellar density, the excitation energy spectrum of the daughter nucleus, and the strength of the Gamow-Teller transitions. The ability of theoretical models to reproduce the locations (and to a lesser degree, the strengths) of the low-lying states that can be captured into, is the most crucial factor in producing reliable electron-capture rates. A good agreement was found between Gamow-Teller transitions calculated using the GXPF1a interaction in the shell-model and the recent data from a high resolution 56Fe(t,3 He) experiment. Since calculations with the KB3G interaction, which forms the basis for a weak reaction-rate library commonly used in astrophysical simulations do worse, it is suggested that improvements can be made to the current inputs for astrophysical models. This conclusion is in agreement with recent results from a 56Ni(p, n) experiment where experimental Gamow-Teller strengths from 56Ni were compared with theory. The procedure outlined in this thesis can be used to further constrain theoretical Gamow-Teller strength calculations with new, successfully developed charge-exchange probes which will be utilized at rare isotope beam facilities such as FRIB.
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