Comparative metrology is a branch of historic metrology where conclusions about ancient systems of measures are drawn based on methods of pure numerical comparison of the actual values of various standards of measurement, or of other artifacts. Typically, no, or very little supporting evidence in form of archeological finds or historical documents are given, the evidence is almost always in form of mathemathics showing relations. The theories are often quite complex, and fail the Occam's razor test.
Interest seems to have been triggered by interest around the Great Pyramid of Giza, and later by the discoveries of standards of measurement in Mesopotamia, especially in Gulash. Resistance against the metric system also seems to have played an important role.