(1) The office of the superintendent of public instruction, in consultation with the state board of education, must:

(a) Calculate the annual extended graduation rate for each high school, which is the rate at which a class of students enters high school as first-year students and graduates with a high school diploma, including students who receive a high school diploma after the year they were expected to graduate. The office may statistically adjust the rate for student demographics in the high school, including the number of students eligible for free and reduced-price meals, special education and English language learner students, students of various racial and ethnic backgrounds, and student mobility;

(b) Annually calculate the proportion of students at grade level for each high school, which shall be measured by the number of credits a student has accumulated at the end of each school year compared to the total number required for graduation. For the purposes of this subsection (1)(b), the office shall adopt a standard definition of "at grade level" for each high school grade;

(c) Annually calculate the proportion of students in each high school who are suspended or expelled from school, as reported by the high school. In-school suspensions shall not be included in the calculation. Improvement on the indicator under this subsection (1)(c) shall be measured by a reduction in the number of students suspended or expelled from school; and

(d) Beginning with the 2012-13 school year, annually measure student attendance in each high school as provided under RCW 28A.300.046.

(2) The office of the superintendent of public instruction may add dropout prevention indicators to the list of indicators under subsection (1) of this section, such as student grades, state assessment mastery, or student retention.

(3) To the maximum extent possible, the office of the superintendent of public instruction shall rely on data collected through the comprehensive education data and research system to calculate the dropout prevention indicators under this section and shall minimize additional data collection from schools and school districts unless necessary to meet the requirements of this section.

(4) The office of the superintendent of public instruction shall develop a metric for measuring the performance of each high school on the indicators under subsection (1) of this section that assigns points for each indicator and results in a single numeric dropout prevention score for each high school. The office shall weight the extended graduation rate indicator within the metric so that a high school does not qualify for an award under RCW 28A.175.145 without an increase in its extended graduation rate. The metric used through the 2012-13 school year shall include the indicators in subsection (1)(a) through (c) of this section and shall measure improvement against the 2010-11 school year as the baseline year. Beginning in the 2013-14 school year, the metric shall also include the indicator in subsection (1)(d) of this section, with improvement in this indicator measured against the 2012-13 school year as the baseline year. The office may establish a minimum level of improvement in a high school's dropout prevention score for the high school to qualify for a PASS program award under RCW 28A.175.145.