Request for help or orientation

Hello. I am new here and I admit I suck at statistics.

I need your help on how to solve a statistical problem. Please don't give the easy answers like "Google it" or "search the forum" because I don't even know the specific keywords to search, and I have been searching this solution for months and I wouldn't be able to identify it even if it bit my ankles.

I work with medical machines and I need to analyse a series of data; for each patient, there is a dosage calculated by four different methods; one depends on the patient physiology, other is fixed (according to sex and age; males under 45 use dosage X, males above 45 use dosage Y, etc), and the other two are directly related to age (eg. 44 years means a dosage of 44% in one system, 22% in the other). I have such data on about 300 different patients.

My problem is: I don't exactly know how to analyse the four parameters to conclude if the physiological one is statistically different from the other three or not.

I need a statistical method to conclude if the physiological method is the most adequate, or if the differences from the other three are so irrelevant that the physiological method has no advantage.

My objective is to be able to say something like "oh! we should prefer the physiological method!" or "meh! it's all the same!"

Can you help me? Thank you.:wave:
One detail: the physiological dosage is calculated for each patient and is independent from other variables (supposedly, each patient has its own specific dosage); the age and half-age methods depend on the age; and the fixed method depends on sex and age.