This grouping criteria allow the reader to have an immediate overview of past vs. current vs. future EGS activities, better appreciate the challenges faced by EGS (technical, economic and related to public acceptance), develop a feeling for the level of research and development efforts put into EGS vis-à-vis the desire to achieve worldwide commercialisation of the concept.
However, compared to the pure description of studies, we feel the criteria enable the reader to better discern between higher and lower quality studies.
For more details on such criteria, we refer the reader to the papers [1, 12, 13, 15, 20, 28, 30, 31, 32, 33] and reference therein.
Unreported exclusion criteria falsely let the reader assume that the results of a trial are more widely applicable.
For more information about the structural-testing criteria mentioned in this section, the reader may refer to seminal studies of structural testing [38, 39]).
A compilation of the best BLAST hits from each searched database is shown in Additional file 4. Figure 2 illustrates how the number of sequences with BLAST hits depends on the significance criteria that are applied, allowing the reader to visualize the number of potentially annotated sequences at varying levels of stringency.
In [40, 43] the reader can find criteria for the approximate controllability of special classes of systems of type (3.3).
In addressing the issue of confounding we remind the reader that two criteria must be met for a variable to be a confounder.
I happen to fit two out of the three criteria - I will leave it to the reader to guess which two.
In this section, we show a quick review about the three more important models in order to remind the reader about those common criteria and, in this way, compare them with the method proposed in this study.
