The different stages of the survey ensure that the process meets the requirements for statistical production:            

• stratified sample selection 

• reminders and checks of data being collected 

• clearance 

• adjustment for total non-response 

• shimming 

• adjustment for partial non-response 

• winsorisation (control of the influence of atypical units)

• the questionnaire was tested (in the 4th quarter 2012) as part of the survey's appearance before the label committee in early 2013.