Ratcliff, D.Williams, E. R.Speed, T. P.2026-01-072026-01-070004-9581https://hdl.handle.net/1885/733803962The Williams & Ratcliff (1980) and Zelen (1957) methods for the analysis of covariance in incomplete block designs with recovery of inter‐block information are compared using data from a balanced incomplete block design. The former is shown to be more efficient. Other advantages of the Williams & Ratcliff formulation are also presented.5en198410.1111/j.1467-842X.1984.tb00457.x84985566444