Data are checked and corrected at an individual level during the collection by the team managing the survey: this team contacts by phone or e-mail units which present some inconsistent or implausible data, in order to validate or to correct it.

After the end of the collection, some more complex checks are applied. This step, called "data cleaning step", also includes some individual corrections.

Finally comes the step of "non-response correction and calibration", which distinguishes the partial non-response correction and the total non-response correction (which aims to change weight units to ensure that the exploitation of the answers will be exactly representative of the scope of the survey).