For the VOY episode with a similar title, please see "Scientific Method".
The scientific method was a set of techniques used in various sciences in correcting, integrating and acquiring knowledge. The basic tenets of the method was to observe a phenomenon, theorize on the cause, and then attempt to prove the theory.
In 2364, Beverly Crusher used the basic scientific method to determine that the microbrain was a living, yet inorganic creature. (TNG: "Home Soil")