Histogram over the distribution of the unstandardized coefficient for the influence of property P on test score change, obtained from estimating regression model (1) in 1,000 simulated datasets in which actual abilities did not change between tests.

<p>Histogram over the distribution of the unstandardized coefficient for the influence of property P on test score change, obtained from estimating regression model (1) in 1,000 simulated datasets in which actual abilities did not change between tests.