After you have entered the data into the file, a time may come when you need to modify your data before analyzing them. You can change the values of individual variables or perform calculations to create new variables out of existing ones. If you do this, you may need to go back and supply new labeling information to describe the modified data. The process depends on the software. If you have done anything to change the data ” such as revising the coding scheme of a variable or simply reading a raw data file into your original format ” you should save a copy of the data in their existing form.