2017 No https://pubmed.ncbi.nlm.nih.gov/28267226/ Ung-Lanki, S Europe Modeling Other Elementary (K-5) Respiratory symptoms Vision Headaches Stress/Anxiety Indoor environment Primary schools Principal component analysis Questionnaire Symptom score Symptoms based on prevalence of symptoms, their test-retest repeatability (ICC), and on principal component analysis (PCA), the number of symptoms was reduced to 17 and six symptoms scores were developed. Six variants of these six symptom scores were then formed and their ability to rank schools compared. Four symptom scores (respiratory, lower respiratory, eye, and general symptoms) analyzed dichotomized maintained sufficiently well the diversity of symptom data and captured the between-school differences in symptom prevalence, when compared to more complex and numerous scores