Although it is possible to clean and validate a database via data input systems, there is a strong case for retrospective checking so that the database is processed for potential problems, oddities and errors.
Errors can slip through even the most stringent of validation procedures.
Very often potential problems are not at all obvious. One of the most common difficulties concerns 'special' characters that database systems can often misinterpret as being separate from the data itself. These can create headaches for a project as well as being rather cumbersome for potential secondary analysts. The essential objective is for creators to ensure within resource limits that their data collection is usable and free of extraneous data. Any correction phase should be relatively short, and this guide will highlight some of the most commonplace problems.