Statistical modelling/Sample size estimation

Expected values of s₁², s₂² and s₃² in the E.M.S. column can be calculated to give:

s₃² = 290.5 (see previous slide but one)
s₂² = (1438.1 - 290.5)/15 = 76.51
s₁² = (2024.8 - 1438.1)/120 = 4.89

Note the relative sizes of s₁², s₂² and s₃². The size of s₁², which represents the contribution from the different buds to the total variation, is very much smaller than s₂² and s₃².

Thus the standard error of the difference (SED) between mean sucrose concentrations, each with 6 x 15 observations, can be calculated as

This is the value given in the output (see previous page).