The existing SIZE Prozess® questionnaire was evaluated in 2007/2008 by Dr. Angelo Giardini (Justus-Liebig University Giessen) and developed further by Fritz Zehetner in cooperation with the University Professor Dr. Thomas Werani (Johannes Kepler University Linz).

The development work of 2008 focused above all on: 

• Validity (relates to the subject of a measurement or investigation)
  
  
• Reliability (relates to the procedure of a measurement or investigation)
  
  
• Relevance of the meaning of the questions (are the questions posed interpreted correctly?)
  
  
• Homogeneity of the questions (can the questions be clearly interpreted by individuals?)
  
  
• Linguistic clarity and precision (is the question sufficiently clear and precise to be understood?)
  
  
• Explorative factor analysis (procedure which is used to identify structures (factors) which underpin a range of items. The aim is to group together similar items and separate them from dissimilar ones.