12-24. Suppose the California Lettuce Research Board conducted a study that followed a randomized complete block design where variety of lettuce (Salinas and Sniper) was the main factor and salinity levels (SAR) were the blocks. The measurements (the number of lettuce heads from each plot) of the kind observed were

SAR Salinas Sniper 3 104 109 5 160 163 7 142 146 10 133 156 a. Determine if blocking was effective for this design.

b. Using a significance level of 0.05, produce the relevant ANOVA and determine if the average number of lettuce heads among the SARs are equal to each other.

c. If you discovered that there were differences among the average number of lettuce heads among the SARs, use the LSD approach to determine which populations have different means.