One symptom of the virus is mouth ulcers. As a result, you're now interested in investigating the oral condition of infected individuals. The data set contains data for a study of oral condition of virus patients. The oral conditions of the patients were measured and recorded at the initial start of the study, at the end of the second week, at the end of the fourth week, and at the end of the sixth week. The variables age, initial weight and initial virus stage of the patients were recorded. Patients were divided into two groups at random: one group received a placebo and the other group received an aloe juice treatment. what nonparametric test should I use?