Adding new or amended variables to a database

Once a project has been flipped, you can add axes or variables to it or replace existing axes or variables with revised versions. Examples of new axes are if extra questions are added to the questionnaire, or if you decide you need some extra information such as the interviewer’s number which was present in the original data but wasn’t flipped. An example of a revised axis is where the axis was incorrectly specified in the original Quantum, or specified in a way that did not produce the best results in Quanvert, and you want to replace the existing version of the axis with a new one.

1 Either update the original Quantum program or write a new Quantum program containing just the new or amended axes or variables, making sure that each axis is mentioned on at least one tab statement. Unless you want to change the default options and titles for the database, keep the options on the a statement as they were for the original database.

Whether you write a new program or just change and rerun the old one is up to you and probably depends on the number and type of changes you want to make.

The merge programs assume that there is no change in the order of the data in the data file between the original flip run and the merge run, and that there is an equal number of cases in each run.

If you are working on a weighted database, do not change the weighting between the original flip run and the merge run. Changes to the weighting, including the definition of new weighting matrices, count as changes to the basic structure of the database and the merge run will fail. If you need to change the existing weighting or define new matrices you must delete the database and recreate it.

Note Quanvert users can also add new variables to a database themselves: Windows-based Quanvert users do this by using the Add data wizard (see the Quanvert User’s Guide); Quanvert Text users do it by using the program qvnewvar. For information about qvnewvar, see the Quanvert Text User’s Manual.