What is the test for an administrative agency's interpretation of a controlling statute?

" If the agency's action depends solely upon the correct interpretation of a statute, that is a question of law upon which the court exercises its independent judgment. [Citation.] In doing so, however, we are guided by the principle that an ' "administrative [agency's] interpretation [of controlling statutes] ... will be accorded great respect by the courts and will be followed if not clearly erroneous." ' [Citations.]" ( Wirth v. State of California (2006) 142 Cal.App.4th 131, 138, 47 Cal.Rptr.3d 623.)