Techniques for processing data sets and, more particularly, constructing a synthetic data set (test data set) from real data sets (input data sets) in accordance with user feedback. The technique mimics real data sets effectively to generate the corresponding synthetic ones. Multiple real data sets may be used to create a test data set which combines the characteristics of these multiple data sets. Users of the technique have the ability to modify the characteristics of the data sets to create a new data set which has features that a user may desire. For example, a user may change the shape or size of, or distort the different patterns in the data to create a new data set. A user may also choose to inject noise into the system.