In an experiment, what purpose does blocking serve?
This question refers to the following learning objective(s):
Identify the four principles of experimental design and recognize their purposes:
control any possible confounders,
randomize into treatment and control groups,
replicate by using a sufficiently large sample or repeating the experiment,
block any variables that might influence the response.
True or False:
Stratified sampling allows for controlling for possible confounders in the
sampling stage, while blocking allows for controlling for such variables during random
Stratifying and blocking both allow for controlling for potential confounders,
but at different stages of the study design. We stratify when we sample (divide
population into strata and sample from within each stratum), and block in the
process of random assignment (divide sample into blocks and randomly assign
from within each block to treatment groups).