The study, conducted by S. Paul Wright, Sandra P. Horn, and William L. Sanders from the University of Tennessee, examines the impact of teacher effects on student achievement while considering classroom context variables such as intraclassroom heterogeneity and class size. Using the Tennessee Value-Added Assessment System (TVAAS), a statistical mixed-model methodology, the researchers analyzed student achievement data from 1994 and 1995 TCAP tests across five subjects and three grades. The results indicate that teacher effects are dominant factors in student academic gain, while classroom context variables have relatively little influence. The study concludes that teachers make a significant difference in student learning and discusses the implications for teacher evaluation and future research. The methodology involves a mixed-model analysis of variance, fitting a complex model to the data to account for various factors affecting student achievement.The study, conducted by S. Paul Wright, Sandra P. Horn, and William L. Sanders from the University of Tennessee, examines the impact of teacher effects on student achievement while considering classroom context variables such as intraclassroom heterogeneity and class size. Using the Tennessee Value-Added Assessment System (TVAAS), a statistical mixed-model methodology, the researchers analyzed student achievement data from 1994 and 1995 TCAP tests across five subjects and three grades. The results indicate that teacher effects are dominant factors in student academic gain, while classroom context variables have relatively little influence. The study concludes that teachers make a significant difference in student learning and discusses the implications for teacher evaluation and future research. The methodology involves a mixed-model analysis of variance, fitting a complex model to the data to account for various factors affecting student achievement.