Repetitions of an experiment or assay are designed to obtain statistical information on the methodological precision of the measurements. A number of repetitions, n, of measurements are performed on the same sample, applying an identical experimental protocol to subsamples, without providing any information on variability between samples.
Contributed by Gnaiger E 2016-02-11
Repetitions versus replica
- Whether repeated measurements are considered as repetitions or replica depends on the delineation between sample and subsample. Repeated measurements on subsamples from a homogenous sample (e.g. a suspension of isolated heart mitochondria) are repetitions, with purely methodological variability. In the case of repeated measurements on heterogeneous samples (e.g. muscle fibres), it is the conceptual question that makes the difference. In most studies on respiration of permeabilized muscle fibres, repeated measurements for fibres obtained as subsamples from the same biopsy or muscle tissue are not designed to study intraindividual variability, but to obtain a more representative result on the individual tissue, frequently only reporting the average of n repetitions. Such 'repetitions', however, may also be considered as replica, if intraindividual tissue heterogeneity is to be studied on the basis of N samples of muscle fibres obtained from the same tissue. In this case, the definition of sample versus subsample has changed, with a focus on variability between tissues versus variability within the (heterogenous) tissue.
MitoPedia O2k and high-resolution respirometry: Oroboros QM