Three sources of variation are considered for their effects on measured variability in foliar analysis of plantation-grown red pine and the concomitant effects of this variability on sample size determinations. The influence of temporal (year-to-year), spatial(site), and treatment (fertilization and irrigation) response variation is discussed. The results indicate that there is a need for a high sampling intensity when the risk, α, that the actual error would be larger than the allowable error, ε, is set at equal to or less than 0.05 and the allowable error, ε, is set at equal to or less than ±10% of the mean for all foliage parameters studied. They also indicate that treatments tended to induce heterogeneity of variances of foliar measurements, increasing the number of samples required at specific risk and allowable error levels over those required if variances on treatment and control plots were homogeneous.
Guidelines on sampling intensity of bees (Hymenoptera: Apoidea: Apiformes)