In recent discussions about teacher evaluation, some people try to distinguish between "subjective" measures (such as principal and peer observations) and "objective" measures (usually referring to value-added estimates of teachers’ effects on student test scores).
In practical usage, objectivity refers to the relative absence of bias from human judgment ("pure" objectivity being unattainable). Value-added models are called "objective" because they use standardized testing data and a single tool for analyzing them: All students in a given grade/subject take the same test and all teachers’ "effects" in a given district or state are estimated by the same model. Put differently, all teachers are treated the same (at least those 25 percent or so who teach grades and subjects that are tested), and human judgment is relatively absent.
By this standard, are value-added models objective? No. And it is somewhat misleading to suggest that they are.