The purpose of the project was to provide machine-readable economic and social history statistics relating to the whole of Ireland for the period 1821-1971. Further information about the project is available on the QUB Centre for Data Digitisation and Analysis website. The main tables are: Irish only speakers and Irish/English speakers grouped by baronies, age groups and gender (1851-1891). Irish only speakers and Irish/English speakers grouped by counties, age groups and gender (1901-1911). Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.