The task of transforming the actual values of data from a source data model to the target data model.

Morcos, John, et al. "Dataxformer: An interactive data transformation tool." Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data. ACM, 2015. [ACM DL]

Data transformations are the application of a mathematical modification to the values of a variable.

Osborne, J. "Notes on the use of data transformations." Practical assessment, research and evaluation 9.1 (2005): 42-50. [CITESEERX]