The phrase "a basic indicator" is correct and usable in written English.
It can be used when referring to a simple or fundamental measure or sign that provides information about a particular situation or condition.
Example: "The temperature is a basic indicator of the weather conditions we can expect today."
Alternatives: "a fundamental sign" or "a primary measure".
The acidity of these concentrated solutions is commonly measured by the acidity function, H0, a quantity measured by the effect of the solvent on a basic indicator I.
Thus, we regard it as a basic indicator to join the model.
Only 38 developing countries, for example, had data on whether malnutrition rates among children were rising or falling – a basic indicator of child health and well-being.
ERK and pERK immunofluorescence was performed as a basic indicator of whether or not SIL could cause phosphorylation within this experimental situation.
This is true even when processing speed is measured by inspection time, a basic indicator of the efficiency of perceptual discrimination that does not depend on motor response speed, memory, or reasoning.
Finally, it should be noted that attention was constantly being drawn to the importance of prevailing morbidity, a basic indicator for assessing medical manpower based on a needs-based approach.
However, this indicator is coupled to the previous one - asking more adults age ≥ 75 about falls in the preceding year (indicator #1) will result in the detection of more high-risk cases requiring a basic evaluation (indicator #2).
However, one more basic indicator pointing towards a chronic disease were the anthropometric measurements.
One driver described train punctuality as a "basic performance indicator for any train driver.
Then he showed a chart he created illustrating the close relationship between movements in stock prices and a basic economic indicator.
We focused on staff number and qualifications for two obvious reasons: data about that is readily available and it is a basic input indicator that affects how well prepared the output (graduates in terms of their knowledge and skills) would be.
