The phrase "a valid subject of" is correct and usable in written English.
It can be used when discussing topics or themes that are appropriate for consideration, analysis, or discussion.
Example: "The ethical implications of artificial intelligence are a valid subject of debate among scholars and practitioners."
Alternatives: "an appropriate topic for" or "a legitimate area of".
There she became convinced that the story of ballet was a valid subject for scholarly investigation.
Anything can be a valid subject for comic treatment but it has to be funny.
When (or whether) men credibly accused of sexual misconduct get to make their comeback is a valid subject.
I don't mean religion, folklore, mythology or eastern esoterica, valid subjects of study though these are.
Further, one boy was excluded because of lacking a valid case control subject.
A clinical comparison of valid subjects was carried out to obtain a mean baseline pain value (mean ± standard deviation) for each arm (X and Y) of the study (X: 6.8 ± 1.9; Y: 5.6 ± 1.9).
A clinical comparison of valid subjects was carried out to obtain a mean baseline pain value for the study population of 3.6 ± 1.8 (mean ± standard deviation), a mean flexion ROM of 64.2° ± 36.5°, and a mean ROM-associated pain value of 2.9 ± 2.6.
The hole-board apparatus appears to avoid this confound, as head-dipping into holes in the floor is assumed to be a valid measure of the subject's attraction towards novelty (neophilia).
If, as shown above, the absence of pain seems to be a valid indicator of the subject's true pathological status, our results show that the reported presence of pain is not as reliable in predicting that shoulder pathology is present.
The Spanish regulator said Google "collects personal information through nearly a hundred services and products offered in Spain, in many cases not providing adequate information about what data is collected, what data is used for what purposes, and without obtaining a valid consent of the data subjects".
