Overall, this analysis of published experimental results provides evidence of both biological processes and confounding methodological effects, and it provides strong arguments for greater rationale in the design of experimental infection studies.
The relatively low contribution of RNA to P in our samples may reflect methodological effects or real differences between these human tissues and the invertebrate and bacterial samples analyzed previously.
To minimize methodological effects interfering with cDNA quantification all total RNA samples were processed in parallel.
Variation in log-ratio values of these un-enriched probes between microarrays therefore reflects methodological effects rather than biology, which compromises their usability.
In this sense, they represent a conservative pair of measures to be used when controlling for methodological effects on the results.
To control for possible methodological effects on FCF and FP content, we recorded the maximum field exposure time (h), canopy cover (% cover, measured with a densiometer) and oven drying time (h) for each sample.
However, a recent large meta-analysis successfully combined amyloid PET and CSF amyloid-β42 data, where individual values were scored as normal/abnormal, successfully across many sites without significant site (and hence methodological) effects (Jansen et al., 2015).
18 We also assessed whether the authors reported a method to investigate non-transitivity, a key to the validity of a network meta-analysis, which occurs when studies are not sufficiently similar in important clinical and methodological characteristics (effect modifiers).
It is possible that the presence of these architectures is attributable to methodological side-effects.
The Cochrane review [ 6] identified methodological confounding effects that may have influenced the study results such as the participants were taking a range of pharmaceutical treatments that may have been altered during the trial and therefore influenced BPSD scores.
