The California Lettuce Research Board was originally formed as the Iceberg Lettuce Advisory Board in 1973.

The primary function of the board is to fund research on iceberg and leaf lettuce. The California Lettuce Research Board published research (M. Cahn and H. Ajwa, “Salinity Effects on Quality and Yield of Drip Irrigated Lettuce”) concerning the effect of varying levels of sodium absorption ratios (SAR) on the yield of head lettuce. The trials followed a randomized complete block design where variety of lettuce (Salinas and Sniper) was the main factor and salinity levels 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.