A primary packaging and publication module within DDI representing the purpose, background, development, data capture, and data products related to a study. In DDI a study is defined as a single coordinated set of data collection/capture activities, such as a one-time survey or a single iteration of a multi-year repeated study (such as one year of a longitudinal survey). The StudyUnit brings together all of the components of the study including the description of its purpose, funding, quality statements, data collection and capture methods and activities, processing activities, and a description of the resulting data (description of its intellectual or logical content plus a description of its physical store). A study unit may have only a single data collection or capture process resulting in one or more data products (i.e., Census). A complex study unit may contain multiple means of data capture that are integrated into one or more data products (i.e., a medical study collecting bio-markers, patient background, health care service information, etc.). A longitudinal study with multiple waves or iterations of data collection is considered to be a group of studies, each wave or iteration captured as a single study unit. As a primary packaging module, the Study Unit contains a full citation, abstract, authorization information, a universe reference, series statement, quality statement, information on post study evaluation, funding information, budget, purpose, coverage, type of analysis units covered, kind of data, other materials, a list of required resource packages, embargoes, the conceptual components (universe, concept, data element, geographic structure and locations), data collection, logical products, physical data products, physical instance, archive, and DDI profile. The maintainable elements within a Study Unit may be included in-line or by reference.