title: Quality control of polysomnographic sleep data by histogram and entropy analysis.
abstract: OBJECTIVE
  Sixteen polysomnographic recordings from 8 European sleep laboratories were analyzed. The histogram analysis was used to introduce quality control of all-night EEG recordings.
  
  
  RESULTS
  It was found that the header information does not always provide the real saturation values of the recording equipment. The entropy measure was used for the quantitative analysis of the dynamic range of routinely used polysomnographic recorders. It was found that the recording equipment provides EEG data with entropy in the range of 8-11 bits.
  
  
  CONCLUSIONS
  In the all-night sleep EEG were observed non-linearities. It is recommended that the equipment provide the saturation values in order to apply automated overflow detection.
authors.affiliation: Institute of Biomedical Engineering, University of Technology, Graz, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Schlögl
authors.forename: B
authors.initials: B
authors.lastname: Kemp
authors.forename: T
authors.initials: T
authors.lastname: Penzel
authors.forename: D
authors.initials: D
authors.lastname: Kunz
authors.forename: S L
authors.initials: SL
authors.lastname: Himanen
authors.forename: A
authors.initials: A
authors.lastname: Värri
authors.forename: G
authors.initials: G
authors.lastname: Dorffner
authors.forename: G
authors.initials: G
authors.lastname: Pfurtscheller
mesh_terms: D006801:Humans; D017286:Polysomnography; D011786:Quality Control; D012890:Sleep / Q000502:physiology*