The phrase "a valid instrument for" is correct and usable in written English.
It can be used when discussing a tool, method, or mechanism that is recognized as legitimate or effective for a specific purpose.
Example: "The new software serves as a valid instrument for improving data analysis efficiency."
Alternatives: "a legitimate tool for" or "an effective means of".
The instrumental variables approach requires a valid instrument for required schooling in addition to the usual instrument for schooling.
Household income rank has been used in other studies as a valid instrument for measured income [ 41, 42] and was considered an appropriate instrumental variable in our study because it is correlated with income and uncorrelated with the error term in the poverty-health relationship [ 38].
The Tracmor is a valid instrument for measuring daily activity in LBP patients.
The PSQI-A is a valid instrument for PTSD applicable to both clinical and research settings.
There would be a benefit in the availability of a valid instrument for its measurement in France.
They also maintain a close relationship with polling firms that produce results that, far from being a valid instrument for measuring electoral tendencies, are in fact electoral propaganda.
The GIS-based model offers a valid instrument for scenic beauty assessments of mountain regions as a basis for policy making and landscape planning.
Computer-assisted formative assessments with multiple-tier items are a valid instrument for diagnosing students' conceptual understanding in learning domains with well-structured declarative knowledge (e.g. science education).
Moreover, also having verified the analytical total stored energy, the analytical model constitutes a valid instrument for the evaluation of the latent and sensible contribution and the trend in time of the position of the bi-phase interface.
The SHSQ-25 is a valid instrument for such purpose.
Only the third scenario (c) exemplifies a valid instrument for X.
