Parents wanting to refuse the SBAC test for their children are running into push back from their school superintendent. Why?

The School Performance Index (SPI). By South Dakota Public School Accountability Index, for elementary schools, 80% of the SPI is based on the SBAC results. For high schools, it’s 50%.

• Why are school accountability models based so heavily on only Math and English?
• We are told the Common Core Standards are just a baseline. A starting point. Why would schools, particularly elementary schools, teach beyond the Common Core?
• Superintendents, school counselors and teachers are very aware of the effect the high stakes test scores will have on their jobs.
• Why would the Department of Education, and the Board of Education agree to a School Performance Index based so heavily on a test based on unproven standards? A test that has no validity studies,  no reliability and questionable cut scores? (Link 1)