ORS 306.120: Uniform methods of assessment and collection; continuing study of equalization.

The Department of Revenue shall:

      (1) Issue regulations, bulletins, manuals, instructions and directions to county assessors, county property value appeals boards and tax collectors as to the methods best calculated to secure uniformity according to law, in the system of assessment and collection of taxes.

      (2) Carry on a continuing study with the object of equalizing for the purposes of assessment and taxation property values within the counties and between the counties.