A better estimate of the internal consistency reliability of frontal EEG asymmetry scores

David N. Towers, John JB Allen

Research output: Contribution to journalArticle

47 Scopus citations


Frontal alpha asymmetry is typically computed using alpha power averaged across many overlapping epochs. Previous reports have estimated the internal consistency reliability of asymmetry by dividing resting EEG sessions into segments of equal duration (e.g., 1 min) and treating asymmetry scores for each segment as "items" to estimate internal consistency reliability using Cronbach's alpha. Cronbach's alpha partly depends on the number of items, such that this approach may underestimate reliability by using less than the number of distinct items available. Reliability estimates for resting EEG data in the present study (204 subjects, 8 sessions) were obtained using mean split-half correlations with epoch alpha power as treated as separate items. Estimates at all scalp sites and reference schemes approached.90 with as few as 100 epochs, suggesting the internal consistency of frontal asymmetry is greater than that previously reported.

Original languageEnglish (US)
Pages (from-to)132-142
Number of pages11
Issue number1
Publication statusPublished - Jan 2009



  • EEG
  • Frontal electroencephalographic asymmetry
  • Reliability

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Experimental and Cognitive Psychology
  • Neuropsychology and Physiological Psychology

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