"a valid indicator" is correct and usable in written English.
You can use it to refer to something that accurately indicates something else. For example, "The decline in sales was a valid indicator that our marketing strategy needed to be changed."
But if the rhetoric from the 17,000 participants from 124 countries at the largest AIDS conference ever held is a valid indicator, there was an overwhelming consensus for supporting prevention and treatment because one cannot work without the other.
In light of this analysis, operability is discussed as a valid indicator of ship safety.
Therefore, propagation power F is a valid indicator of the risk of virus propagation.
However, Graham (1987) questioned whether GPA was always a valid indicator of academic performance.
That is, individual physician wellness is a valid indicator of organizational health [13, 36].
We propose that excess risk-adjusted, postoperative length of stay (poLOS) is a valid indicator of an adverse outcome.
Self-rated health (SRH) is known to be a valid indicator for the prediction of health outcomes.
The quantitative information provided by instrument was deemed to be a valid indicator of activity timing and modification.
However, lac appeared in many Persian carpets, and its use would not be seen as a valid indicator of origin.
Two listening experiments were conducted in order to determine whether A-weighting is a valid indicator of the perceived loudness or annoyance of road-traffic sound.
More critical, biological questions including whether convergence of taxa abundance and composition is a valid indicator of similar ecological function remain to be answered.
