The phrase "a primary indicator" is correct and usable in written English.
It can be used when referring to a key sign or measure that provides important information about a particular situation or condition.
Example: "The unemployment rate is often considered a primary indicator of the health of the economy."
Alternatives: "a key measure" or "a main sign".
Consumer spending, which economists often look to as a primary indicator of recovery, grew 2percentt.
High wetness state levels can be considered as a primary indicator for potential river flooding.
Adsorption of iodine and methylene blue was used as a primary indicator of the adsorption capacity of these carbons.
Limnologists and hydrobiologists are attentive to the dissolved oxygen content of the water because it is a primary indicator of water quality.
The progress of such mapping in the various parts of the world is therefore a primary indicator of the status of cartography in general.
In the present study, the authors investigated whether such variations could induce changes in the microvascular flow, which is considered a primary indicator of poor perfusion.
Getting to a call within the allotted time – a major target discussed by every borough's senior management as the primary indicator of a day's successful policing – has become more important than the reason for attending the call in the first place.
In its report, the committee cited the real gross domestic product -- the value of all goods and services in the economy, adjusted for changes in prices -- as the primary indicator of a recovery.
Population size in a geographical area is the primary indicator of need [ 13].
Because it is relatively easy to measure thyroid hormone concentrations, most studies to date use circulating levels of thyroid hormone as the primary indicator of an effect on the thyroid system, or focus on mechanisms by which contaminants could affect thyroid hormone levels.
Walking capacity is a primary outcome indicator for individuals with lumbar spinal stenosis (LSS).
