The phrase "age as a proxy" is correct and usable in written English.
It can be used in contexts where age is being used as a substitute or indicator for another variable or characteristic.
Example: "In this study, we used age as a proxy for maturity to analyze behavioral differences among participants."
Alternatives: "age as a substitute" or "age as an indicator".
So insurers are using age as a proxy for health.
They have been heavily lobbied for exemptions by private companies such as insurance firms that use age as a proxy for risk.
Any use of age as a proxy for ability and competence is discriminatory and will penalise people who are perfectly able and capable to go on doing their jobs and contributing to the success of the organisations they work for.
Bruichladdich's ten-year problem was partly a marketing problem: malt drinkers have come to view age as a proxy for quality, and the industry has played along, using age statements to justify high prices.
Therefore, we have to use age as a proxy to control work experience.
For example, Kidd ([1993]) used age as a proxy for financial capital and adopted a binary variable, "rent", to study immigrants' propensity for self-employment.
Because ferritin may be influenced by menopause, we stratified by age (45 years as a proxy cut-off for pre- and postmenopausal age).
We stratified for age (45 years as a proxy for the pre/postmenopausal cut-off) in the Andean group because the population included women from 12 to 80 years of age and because menopause might influence ferritin and other factors that might confound associations between genotypes and Cd metabolism.
Furthermore, we examined the association between H1N1 vaccination and insulin dependent diabetes in people born from 1990 onwards (onset at age ≤20 years) as a proxy for type 1 diabetes.
To investigate the role of body mass in early adulthood as a potential confounder vs mediator, we used BMI at age 25 as a proxy measure and stratified the analysis by the age at which women had given birth to their first child (considering an age of either ≤24 or ≥26 to define subgroups) (ESM Table 4).
The explanatory variables were age at thelarche, age at menarche, age at regular periods, age when reached adult height, the intervals between these ages, and growth spurt in height between ages 7 and 11 years (as a proxy for peak growth).
