The phrase "a valid and functioning" is correct and usable in written English.
You can use it to describe something that is both acceptable and operational, often in technical or formal contexts.
Example: "The software must be a valid and functioning application to ensure it meets the project requirements."
Alternatives: "a legitimate and operational" or "an acceptable and working".
The general functioning scale has been shown to be a valid and reliable measure of family functioning in surveys [ 6].
It is clear from this figure that the derived PDF of γ up is a valid and a non-negative function.
The GAF, which in our application consists of only two ratings (psychopathology and impairment), is recognised as a valid and comprehensive measure of social functioning when used in routine clinical practice [ 17, 18] and in research [ 17, 26].
Blood was drawn for cytokines through days 7. Cohort 2 underwent strength and physical functional assessments using the Short Physical Performance Battery (SPPB), a valid and reliable measure of physical function consisting of walking speed, balance, and repeated chair stands.
Third, the system needs a stronger research base in order to function as a valid and reliable indicator of quality (Elliott, 2004; Ishimine et al., 2009).
Studies have found the PRWE to be a valid and responsive questionnaire regarding wrist function [ 7, 8].
A recent paper described the OSS as a valid and feasible measure of shoulder function in patients with rheumatic diseases who undergo shoulder surgery (Christie et al. 2009).
Does the FRAS function in a valid and reliable way?
Numerous studies over the past 40 years have supported its utility as a valid and reliable indicator of general cognitive function [ 5].
In this paper, we report on our study of the psychometric properties of the FRAS instrument, in which we formally addressed two research questions: Does the FRAS function in a valid and reliable way?
