Mass. Gen. Laws ch. 58, § 6: Real estate values; collecting information

Section 6. The commissioner may collect and tabulate information as to the classification, sales price and fair cash value of real estate in the several towns. For this purpose he may require assessors to furnish him with any information in their possession, may consult persons likely to have knowledge as to the classification, sales price and fair cash value of separate parcels of real estate, and may examine probate and other relevant records.