A Harmonization protocol documents and annotates a set of core variables which provides a concise but effective list of information to be harmonized in a specific scientific context. Variables found in a Harmonization Dataset therefore represent the reference format into which study-specific data needs to be processed to arrive at harmonized data. When a study can generate a variable defined in a Harmonized Dataset, a processing algorithm is developed to map study-specific data to the variable format defined in the Harmonized Dataset.