Overview of Minimum Group Size Business Rules for State Accreditation

1. Overview of Minimum Group Size Business Rules for State Accreditation April 23, 2019 Dr. Jennifer Piver-Renna Director of Research

2. Minimum Group Size Defined • Institute of Education Sciences (IES) defines minimum group size as the “lowest statistically defensible subgroup size that can be reported in an accountability system with protections for personally identifiable information”1 • Also referred to as minimum n size or small n • Important for understanding and holding schools accountable for the underperformance of disadvantaged groups that may otherwise be hidden in aggregate data • IES publishes a best practice guide for determining minimum group size, but is prohibited from defining a specific number of students in a subgroup (1) Institute of Education Sciences. (2017). Best Practices for Determining Subgroup Size in Accountability Systems While Protecting Personally Identifiable Student Information. https://nces.ed.gov/pubs2017/2017147.pdf

3. Minimum Group Size in State Accreditation • Inclusion of achievement gap indicators prompted the Department to re-examine minimum group size rules for state accreditation • In January through August 2018, the Department modeled and solicited feedback on multiple minimum group size scenarios • Influenced by decisions in federal accountability: • 16 states/territories have a minimum group size of 10 • 28 states/territories have a minimum group size between 11 and 25 • 8 states/territories have a minimum group size of 30, including Virginia

4. Minimum Group Size Business Rules for State Accreditation • Student groups are evaluated in state accreditation when: • The student group includes 30 or more students in the current year OR • The student group includes 30 or more students across three years OR • The student group includes less than 30 students and is rated Level One or Level Two • Final business rules determined by Department’s SOA Implementation Committee and are documented in the Calculating Accreditation document available to school divisions

5. Justification for Business Rules • The current year minimum group size threshold is the same for federal accountability, but pooling across three years allows the Department to include the performance of more students in state accreditation • Small groups of well-performing students are considered in state accreditation • Schools where student groups have not met state benchmarks based on the combined rate or have not meaningfully reduced the failure rate will be identified for support