title: Experimental versus evaluation unit and multiplicity problem in cell biology study.
abstract: Yizraeli and Weihs, Cell Biochem Biophys, 61: 605-618, 2011 evaluated the effect of electrical treatment on proliferative metabolic-activity of three experimental cell conditions. They reported, that the "...three independent experiments were done in triplicate (three samples in parallel, O.V.) for each condition...", in three time-points. Therefore, I suggest, that any three samples in parallel (triplicate) in the same experiment shared more similar environmental conditions compared to any three samples (no triplicate) from three different independent experiments. Moreover, the absence of basic statistical information in the manuscript of Yizraeli and Weihs (2011) might be associated with hidden common statistical errors: (a) implicit pseudoreplication due to incorrect determination of the experimental and evaluation units and (b) simultaneous inference without correction of p-values due to ignoring the overall type I error rate.
authors.affiliation: Faculty of Biomedical Engineering, Technion, Israel Institute of Technology, 32000, Haifa, Israel. verbitskyoleg@gmail.com
authors.forename: Oleg
authors.initials: O
authors.lastname: Verbitsky
mesh_terms: D003585:Cell Biology; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D002477:Cells / Q000166:cytology / Q000378:metabolism; D055724:Electrophysiological Phenomena; D006801:Humans; D015203:Reproducibility of Results; D012107:Research Design; D013997:Time Factors