Data sheets and questionnaires always contain questions that respondents can answer spontaneously. We render numbers to each answer, which clearly defines the various answer categories. The quality of coding strongly depends on coders’ competence in the topic of the research, so we start coding after thorough professional preparation only.

Answers in printed or coded form or marked with numbers are to be transformed into electronic, that is, assessable data format. In an ideal case, data matrix contains only numbers because during coding, we have already rendered an easily identifiable identifier.

During clinical tests of different phase, checking of data entry is essential. After finishing data entry, all information are transformed into electronic form without loss, and data processing can start after that.

We can organize the entered data base of several research projects, with the help of which data can be handled consistently, and individual data structures can be created by optional queries and data storing is safe and it is easy to archive them.