R package MCI. The Multiplicative Competitive Interaction (MCI) Model by Nakanishi &amp; Cooper (1974) &lt;<a href=””>doi:10.2307/3151146</a>&gt; is an econometric model for analyzing market shares and/or market areas and is closely related to the Huff model. The functions in this package include fitting the MCI model, MCI shares simulations, the log-centering transformation of MCI datasets, creation of interaction matrices and tools for data preparation. Additionally, the package provides applications for the Huff model, including a non-linear fitting algorithm.