This report concerns the use of a preliminary test of equality of regression slopes in two-sample simple linear regression datasets for the purpose of deciding whether to pool the two datasets and perform a single analysis. This work was performed as a supplement to the paper of Shao, Slud et al. (2014), The latter paper cites this one as a Census Bureau preprint of 2012, and applies its results in the context of model-assisted design-based survey eastimation. For a broader overview of estimation following preliminary testing, see the book of Saleh (2006).