Tex. Tax Code § 5.10

(a) At least once every two years, the comptroller shall conduct a study in each appraisal district to determine the degree of uniformity of and the median level of appraisals by the appraisal district within each major category of property. The comptroller shall publish a report of the findings of the study, including in the report the median levels of appraisal for each major category of property, the coefficient of dispersion around the median level of appraisal for each major category of property, and any other standard statistical measures that the comptroller considers appropriate. In conducting the study, the comptroller shall apply appropriate standard statistical analysis techniques to data collected as part of the study of school district taxable values required by Section 403.302, Government Code.

(b) The published findings of a ratio study conducted by the comptroller shall be distributed to all members of the legislature and to all appraisal districts.

(c) In conducting a study under this section, the comptroller or the comptroller's authorized representative may enter the premises of a business, trade, or profession and inspect the property to determine the existence and market value of property used for the production of income. An inspection under this subsection must be made during normal business hours or at a time mutually agreeable to the comptroller or the comptroller's authorized representative and the person in control of the premises.