Clinical Trial Laboratory Data Nested With in Subject: Components of Variance, Sample Size and Cost

Nesting of experimental factors is well established in statistical design literature related to agricultural, environmental and engineering studies. It is perhaps not sufficiently discussed in biological and laboratory experiments stemming from the use of human bio-specimens, where sample size considerations are often provided a priori on subject level, but there is little advice regarding the needed number of units at lower levels. Motivated by an example from spectroscopic microscopy and lung cancer, we revisit the experimental nesting frame work and discuss how variability, cost of sampling and sample size at lower levels may be coherently utilized. We show how the number of subjects may have to be adjusted to account for inadequate sampling decisions made at lower levels.