text: Many national surveys and statistical evaluations add to this, often with more detail and closely related 
  to the national economic and political infrastructure and its working conditions legislation. The different 
  national situations to which the institutes refer to and the different methodologies that the national 
  institutions use make it hard to impossible to compare countries based on these national data. 458 
  However, the differences seem to be minor if the questions in European or national surveys are very 
  similar. 