However, should these groups not be independent, and there is an order in the groups (such as mild, moderate and severe disease), or in the dose of a drug (such as 5 mg/mL, 10 mg/mL, 20 mg/mL) given to the same group of patients, then a linear trend estimation should be used.
Nevertheless, if these groups are not autonomous, and there is a sequence in the groups (like mild, moderate, and severe illness), or in the dosage of a medication (such as 5 mg/mL, 10 mg/mL, 20 mg/mL) administered to the same set of patients, then a linear trend estimation ought to be employed.