Professional Contrast Coding for OLS Models // Automates sum coding (also known as effect coding) for Ordinary Least Squares (OLS) regression models. This approach is specifically designed to handle seasonal time series and categorical variables by comparing each group to the grand mean, rather than a single baseline category. This ensures that the intercept represents the unweighted grand mean of the dependent variable. For a comprehensive overview of contrast coding systems, see the UCLA Advanced Research Computing documentation (2021) https://stats.oarc.ucla.edu/r/library/r-library-contrast- coding-systems-for-categorical-variables/.