The phrase "are a robust indicator" is correct and usable in written English.
It can be used when discussing something that serves as a strong or reliable sign of a particular condition or trend.
Example: "The consistent increase in sales figures are a robust indicator of the company's growth potential."
Alternatives: "serve as a strong indicator" or "act as a reliable sign".
Finally, comparisons of WTR calculations against a more complex 3D regional groundwater flow model have indicated that the WTR is a robust indicator of groundwater's connection to the land surface as it is a strong predictor of the propensity for local versus regional flow conditions50.
While our results allow us to conclude that degree alone is a robust indicator for a proteins propensity to be evolutionary conserved, the inherent topological robustness of locally clustered links emphasizes the emergent role of cohesive areas [ 26] as mediators of evolutionary information.
Because the only source of 232Th to the ocean is continental minerals, this proxy is a robust indicator of continental weathering.
The relative enrichment of Th over U implies that Th/U ratio may not always be a robust indicator of crystallization environment.
The differential enrichment of Th over U illustrates that deformation-enhanced diffusion could potentially result in the significant modification of Th/U ratio, and implies that Th/U ratio may not always be a robust indicator of primary crystallization environment.
It is clear from the comparison of the measured High Plains aquifer chemistry and the calculated aquifer water chemistry, that pH is a robust indicator of an influx of CO2 into a dilute aquifer from a much deeper carbon sequestration reservoir.
The return on investment in adult education is a robust indicator of the successes that can be found through targeted funding streams.
The number of steps is a robust indicator of the actual execution time (see barometer instruction technique [14]).
Thus, the ranking of a journal in a field, based on Eigenfactor score, is a robust indicator of the overall influence of the journal within the field [27].
This was possible because cardiac output (CO) is a robust indicator of metabolic rate [20] and Antarctic fish modulate CO chiefly by changes in fH [21].
