In early 2024, I published a blog post exploring how machine learning could predict Tennessee school letter grades based on demographic data. That analysis provided insight into the structural factors influencing school performance metrics, particularly the significant role of economic disadvantage. Since then, I’ve expanded the dataset to include both the 2023 and 2024 school letter grades, refining the model to capture trends over time and further assess the predictive power of demographic variables. This post serves as an update on that work and a precursor to a more detailed research paper.
Revisiting the Predictive Model
Tennessee assigns letter grades (A–F) to schools based on multiple criteria, including student achievement, academic growth, and college/career readiness. While these grades are intended to reflect school quality, they often correlate strongly with socioeconomic and demographic factors.
For this updated analysis, I merged data from both years to improve model robustness. The methodology remained consistent:
Data Collection: Letter grades and demographic data were sourced from the Tennessee Department of Education.
Data Processing: Letter grades were converted to a numeric scale, and missing values were cleaned.
Machine Learning Models:
Random Forest Regression for feature importance analysis
Linear Regression to estimate the impact of individual factors
Correlation Analysis to identify relationships between variables
Letter Grade Scale
A 4.5-5.0
B 3.5-4.4
C 2.5-3.4
D 1.5-2.4
F 1.0-1.4
Key Findings
Economic Disadvantage Remains the Strongest Predictor
Schools with higher percentages of economically disadvantaged students continue to receive lower letter grades. The model estimates that for every 10% increase in economically disadvantaged students, the expected letter grade drops by 0.35 on a 1.0–5.0 scale.
Special Education Enrollment Also Impacts Letter Grades
The presence of students with disabilities (SWDs) is another contributing factor, though to a lesser extent. A 10% increase in SWD enrollment is associated with a 0.11-point decrease in letter grade.
Race and Economics Are Closely Linked
Schools with higher percentages of Black, Hispanic, and Native American students tend to have lower grades. However, when controlling for economic disadvantage, racial composition becomes a less significant predictor. This suggests that economic factors, rather than race itself, drive these disparities.
See the correlation matrix below:
Demographics Explain About One-Third of Grade Variation
The updated linear regression model explains 29% of the variance in school letter grades, meaning that while demographics play a measurable role, other factors—such as instructional quality, funding, and school leadership—are also crucial.
What If Demographics Were Removed?
A simulated model scenario where a school had no economically disadvantaged students and no SWDs predicted an average letter grade of 4.5 (A range). This reinforces the idea that many low-performing schools face structural challenges beyond their control.
Public Schools: A Testament to Resilience
In the context of Tennessee’s voucher era, public schools operate under significantly different—and often more challenging—conditions than private schools, making their achievements all the more remarkable. The assumption that private schools inherently provide a superior education doesn’t hold up under scrutiny.
Unlike private institutions, which can be selective in their admissions, public schools serve every student—regardless of economic status, disability, or other challenges. Private schools often have the luxury of limiting enrollment to students who fit their preferred criteria, while public schools are tasked with educating all children who walk through their doors—often with fewer resources and greater accountability.
Despite these challenges, many public schools deliver exceptional outcomes. Educators work tirelessly to support students from diverse backgrounds, implementing innovative instructional strategies and targeted interventions to ensure student success. Their ability to foster academic achievement and social growth, even in the face of structural obstacles, speaks to the public education system's resilience, dedication, and effectiveness.
Public schools should be celebrated rather than maligned for their role in serving all students, strengthening communities, and proving that educational excellence is not exclusive to selective institutions.
This blog post was proofread with suggested corrections by Grammarly.
