The NVPI comprises three questions

The NVPI comprises three questions that ask the participant to evaluate the frequency of nausea, retching, and vomiting symptoms during the past week. Items are scored on a six-point Likert scale from 0 to 15. Higher scores indicate more severe symptoms. The instrument has acceptable internal reliability at two gestational time periods with a Cronbach’s alpha coeffient of 0.76 at Time 1 and 0.82 at Time 2. The teat-retest reliability was high, although only a small sample completed the instrument twice (0.83; 95% confidence intervals 0.71-0.90) (Swallow,Lindow,Masson,&Hay,2002).