Proper experimental design requires randomization/balancing of molecular ecology experiments

Properly designed (randomized and/or balanced) experiments are standard in ecological research. Molecular methods are increasingly used in ecology, but studies generally do not report the detailed design of sample processing in the laboratory. This may strongly influence the interpretability of results if the laboratory procedures do not account for the confounding effects of unexpected laboratory events. We demonstrate this with a simple experiment where unexpected differences in laboratory processing of samples would have biased results if randomization in DNA extraction and PCR steps do not provide safeguards. We emphasize the need for proper experimental design and reporting of the laboratory phase of molecular ecology research to ensure the reliability and interpretability of results. Properly designed (randomized and/or balanced) experiments are standard in ecological research, but laboratory experiments in molecular ecology do not report the detailed design of sample processing in the laboratory. Confounding effects of unexpected laboratory events may strongly influence the interpretability of results, as we demonstrate this with a simple experiment. Only proper experimental design and reporting of the laboratory phase of molecular ecology research ensure the reliability and interpretability of results.