Abstract
Randomised experimental designs are considered statistically advantageous for many scientific applications, as they reduce the effect of problematic parameters such as sample position. The effect of randomisation was assessed using real-time PCR experiments for the determination of genetically modified material. Replicate microtitre plates using a randomised design were compared with replicate microtitre plates that contained the same samples allocated in a systematic fashion to experimental position within the plate. Results indicated that randomisation would help reduce between-plate variability and would give advantages in intra-laboratory studies. However, these benefits may be less effective for inter-laboratory studies as the between-laboratory variability often far exceeds the between-plate variability.
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Notes
Additional strategies, such as blocking or latin square designs, can provide greater benefits for comparisons within an experiment than randomisation alone if nuisance effects are likely to apply to identifiable groups of observations (the presence of consistent row effects in 96-well plates would be a good example). This is, however, beyond the scope of the present paper.
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Acknowledgments
The authors thank Hernan Valdivia (LGC) for his valuable contribution with respect to conducting the practical work associated with the experiments. The work described in this paper was funded in part by the UK National Measurement System. The authors gratefully acknowledge funding provided by the 6th EU Framework Programme for Research and Technological Development (FP6) project ‘GM and non-GM supply chains: their CO-Existence and TRAceability” (Contract number 007158).
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Burns, M., Ellison, S. The fitness for purpose of randomised experimental designs for analysis of genetically modified ingredients. Eur Food Res Technol 233, 71–78 (2011). https://doi.org/10.1007/s00217-011-1485-x
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DOI: https://doi.org/10.1007/s00217-011-1485-x