Assessing non-specific symptoms in epidemiological studies: Development and validation of the Symptoms and Perceptions (SaP) questionnaire
Keywords: شیره; SaP; Symptoms and Perceptions (questionnaire); NSS; non-specific symptoms; GP; general practitioner; ICPC; International Classification of Primary Care; B-IPQ; brief Illness Perceptions Questionnaire; PCA; principal component analysis; ROC; receiver opera