New to ARM are spatial biplots. Biplots are a common diagnostic tool in treatment by trial interaction analysis, but not commonly used in spatial modeling. To illustrate, we will use data from two trials.

Effective spatial model

Ineffective spatial model

Linked are the diagnostics plots for Column 2 (Second); scroll to the spatial plots on page 3. The first file contains diagnostics for raw assessment data and the design (IID) AOV model; the second compares IID with the AIC preferred cubic spatial trend CST model.


Cochran, W G. 1947. “Some Consequences When the Assumptions for the Analysis of Variance Are Not Satisfied.” Biometrics 3 (1): 22–38.

Cochran, William G, and Gertrude M Cox. 1957. Experimental Design. Vol. 2. John Wiley; Sons, Inc.