(1) For the purposes of applying the severe discrepancy tables, the following scores shall be used:

(a) A total or full scale intellectual ability score;

(b) An academic achievement test score which can be converted into a standard score with a mean of one hundred and a standard deviation of fifteen; and

(c) A severe discrepancy between the student's intellectual ability and academic achievement in one or more of the areas addressed in WAC 392-172A-03055(1) shall be determined by applying the regressed standard score discrepancy method to the obtained intellectual ability and achievement test scores using the tables referenced above.

(2) Where the evaluation results do not appear to accurately represent the student's intellectual ability or where the discrepancy between the student's intellectual ability and academic achievement does not appear to be accurate upon application of the discrepancy tables, the evaluation group, described in WAC 392-172A-03050, may apply professional judgment in order to determine the presence of a specific learning disability. Data obtained from formal assessments, reviewing of existing data, assessments of student progress, observation of the student, and information gathered from all other evaluation processes for students being identified for a specific learning disability must be used when applying professional judgment to determine if a severe discrepancy exists. When applying professional judgment, the group shall document in a written narrative an explanation as to why the student has a severe discrepancy, including a description of all data used to make the determination through the use of professional judgment.