Teacher bias or measurement error bias? Evidence from track recommendations

This study examines to what extent measurement error in test scores explains track recommendation bias in the Netherlands. Track recommendations play an important role in allocating children to secondary school tracks. However, track recommendations are subjective evaluations of a child's skills and have been criticized for being biased. Previous studies have shown that children from low socio-economic status (SES) families receive lower track recommendations than their peers from high SES families, conditional on standardized test scores. While it is often argued that this is evidence of teacher bias, such a claim is invalid in the presence of (random) measurement error in test scores. Standardized tests measure the child’s true skills with error and the resulting measurement error bias spills over to the estimates of SES differences. This study corrects for measurement error bias in test scores by applying an instrumental variable strategy. The findings show that models that do not address measurement error in test scores substantially overestimate low-high SES differences in track recommendations. Overall, the presumed teacher bias can to a large extent be explained by measurement error in test scores.