On the Use of Ranks for Testing the Coincidence of Several Regression Lines

Abstract

For several linear regression lines $Y_{ij} = \alpha_i + \beta_i(x_{ij} - x{_i.}) + Z_{ij}, i = 1,\cdots, k; j = 1, \cdot, n_i$, a statistic for testing $\alpha_i = \alpha, \beta_i = \beta$ is constructed based on the simultaneous ranking of all the observations. The asymptotic properties of the criterion are also studied. The results are, however, not directly applicable to the general design model $Y_{ij} = \alpha_i + \beta_i x_{ij} + Z_{ij}$, unless it is assumed that the group means $x_i$. are all equal.