Jeffrey C. Schiman

Instruction Time, Classroom Quality, and Academic Achievement

It seems likely the magnitude of any causal link between achievement and instruction time depends upon the quality of instruction, the classroom environment and the rate that students translate classroom time into added knowledge. In this article, we use panel data methods to investigate instruction time effects in the 2009 Programme for International Student Assessment data. The empirical analysis shows that achievement increases with instruction time and that the increase varies by both the amount of time and the classroom environment. The results indicate that school circumstances are important determinants of the benefits and desirability of increased instruction time.

Comparing Standard Deviation Effects across Contexts.

ABSTRACT Studies using tests scores as the dependent variable often report point estimates in student standard deviation units. We note that a standard deviation is not a standard unit of measurement since the distribution of test scores can vary across contexts. As such, researchers should be cautious when interpreting differences in the numerical size of point estimates when comparing across contexts. We empirically assess the importance of this issue both within the United States and internationally.