Body: People who study "Empirical research methods in linguistics" investigate indirect and direct observation or experience.
Some motivations are understand the art of researching, know and how effective it is.
Some subfields in "Empirical research methods in linguistics" include Why is it called empirical research? What is direct and indirect observation?, Bias in basing research mainly on one experience.
A few notable experts of "Empirical research methods in linguistics" include Adriaan de Groot, Dayton, C. Mitchell.