The Environmental Symptoms Questionnaire: corrected computational procedures for the alertness factor

The Environmental Symptoms Questionnaire (ESQ) provides a systematic and quantitative measurement of acute mountain sickness (AMS) as well as other symptoms resulting from exposure to various climatic or stressful conditions. The questionnaire yields factor scores for nine distinct symptom groups. The computational procedures for one of the factors, Alertness, were incorrect as reported in the original manuscript (2). This paper gives the correct procedures and their rationale.