Refer to your results from Exercise 1 in Chapter 2. Examine the output produced by the analysis of variance to determine the effects of variety and nitrogen level in a split plot design.

(a) Obtain the SE for the difference between the mean yields for the following factor levels or combinations of levels: (i) nitrogen Level 1 vs. nitrogen Level 3 (ii) variety ‘Victory’ at nitrogen Level 1 vs. variety ‘Victory’ at nitrogen Level 3 (iii) variety ‘Victory’ at nitrogen Level 1 vs. variety ‘Golden Rain’ at nitrogen Level 3.

(b) Obtain the LSD at the 5 % level between variety means. Are there any two varieties that are significantly different according to this criterion?

(c) Obtain the SE for nitrogen-level means on the following bases: (i) conditional on the blocks and main plots (ii) taking into account the random effects of blocks and main plots.