Photos of various sampling techniques that cause uncertainty in measurements, which can all be estimated using the 'duplicate method'.
Sampling for organic contamination at a gas-works site
Extracting soil from a 'window' sampler in a domestic garden
Sampling a stock pile of contaminated soil
The 'W' design applied to a bay of 20,000 lettuce samples. Ten heads of lettuce are taken along the line of the W to create a composite sample for nitrate determination (See Eurachem Guide page 35)
Sampling 20 tons of butter in an experiment to estimate uncertainty caused by sampling bias (Ramsey et al., 2011)