The data are based on the 2011 Census Microdata Teaching File, with the first 18 variables in the OriginalTeachingFileData worksheet exactly the same as those found in the original file. This can be downloaded from: http://www.nisra.gov.uk/Census/2011_results_specialist_products.html. It is also available on the Northern Ireland Neighbourhood Information Service (NINIS) website.The final 8 variables found in the SYLLS_Synthetic_NILS_Spine worksheet, are synthetic data. Those variables corresponding to a 2001 state are based on the transitional probabilities taken from the NILS, accurate to 10 year age groups.