"This pictorial (Baxter Retching Faces) scale for measuring nausea severity has convergent and discriminant validity, and detected change after antiemetic treatment. Its use in the clinical and research setting may assist in nausea managment in children."

Reference: Baxter, A. L., Watcha, M. F., Baxter, W. V., Leong, T., & Wyatt, M. M. (2011). Development and Validation of a Pictorial Nausea Rating Scale for Children. Pediatrics, 127(6), e1542-e1549.

http://pediatrics.aappublications.org/content/early/2011/05/25/peds.2010-1410