The ratio hypothesis is obtained directly from the linear hypothesis by
division by 2,; hence if the linear model (3) is true and the ratio model (4) is
fitted, the assumption of homoscedasticity of the residuals from the correct
model implies that the residuals from the incorrectly specified model cannot
be homoscedastic. To distinguish between (3) and (4) it appears natural to test
both models for homoscedasticity. The following possibilities arise : (a) we
cannot reject the hypothesis of homoscedasticity in either case. We shall then
suspend judgment as to which model is preferable. (b) We reject the hypothesis
of homoscedasticity for one but not the other case. We shall then accept the
formulation leading to homoscedastic residuals as the true one. (c) We reject