Comparing global judgments and specific judgments of teachers about students' knowledge: Is the whole the sum of its parts?

Teachers' judgments about students' knowledge and skills can be global or specific depending on the diagnostic situation during teaching. We test the relationship between these judgments, their accuracy, and whether global judgment (GJ) accuracy can be measured by aggregating specific judgments (SJ). Judgments of 52 primary school teachers about their students' achievement in a standardized mathematics test were assessed. SJs and GJs correlated high. However, SJs were slightly more accurate than GJs. Additionally, teachers' GJ accuracy is not similar to the accuracy of aggregated SJs. We conclude that teachers use different judgment strategies for GJs and SJs.