Tax Code §1.12

(a) For purposes of this title, the median level of appraisal is the median appraisal ratio of a reasonable and representative sample of properties in an appraisal district or, for purposes of Section 41.43 or 42.26 , of a sample of properties specified by that section. (b) An appraisal ratio is the ratio of a property's appraised value as determined by the appraisal office or appraisal review board, as applicable, to: (1) the appraised value of the property according to law if the property qualifies for appraisal for tax purposes according to a standard other than market value; or (2) the market value of the property if Subdivision (1) of this subsection does not apply. (c) The median appraisal ratio for a sample of properties is, in a numerically ordered list of the appraisal ratios for the properties: (1) if the sample contains an odd number of properties, the appraisal ratio above and below which there is an equal number of appraisal ratios in the list; or (2) if the sample contains an even number of properties, the average of the two consecutive appraisal ratios above and below which there is an equal number of appraisal ratios in the list.