Testing equality of two intercepts for the parallel regression model with non sample prior information

This paper proposes tests for equality of intercepts of two simple regression models when non sample prior information is available on the equality of two slopes. For three different scenarios on the values of the slope, namely (i) unknown (unspecified), (ii) known (specified), and (iii) suspected, we derive the unrestricted test (UT), restricted test (RT), and pre-test test (PTT) for testing the equality of intercepts. The test statistics, their sampling distributions, and power functions of the tests are obtained. Comparison of power function and size of the tests reveals that the PTT has a reasonable dominance over the UT and RT.