The phrase "a proportionate increase" is correct and usable in written English.
It can be used when discussing a change or growth that is relative to a certain baseline or context, often in statistical or financial discussions.
Example: "The company reported a proportionate increase in sales following the new marketing campaign."
Alternatives: "a relative increase" or "an equivalent rise".
Our work showed that an increase in badger numbers does not lead to a proportionate increase in TB.
The remaining centers will have to serve up to 71 percent more patients, without a proportionate increase in staff, according to city figures provided to aldermen.
Returns to scale, in economics, the quantitative change in output of a firm or industry resulting from a proportionate increase in all inputs.
However, following recent share price weakness (which has not been accompanied by a proportionate increase in company-specific risk), we see the stock's risk/reward as increasingly compelling and add the stock to our buy list.
While Mr. Abrams said the mayor could spend more money on opera at the expense of all the museum financing, he could not spend more on the Metropolitan without giving a proportionate increase to the Brooklyn Museum.
For instance, a recent article in The American Economic Review by Gilles Duranton and Matthew Turner shows that road construction in the United States typically leads to a proportionate increase in utilization, leaving congestion unchanged.
However, a large proportionate increase is easier from a low starting level since a small absolute rise can become a large proportion.
The changes in hours that was meant to bring more women into the chamber has merely led to a tiny proportionate increase, and instead of a busy bustling parliament the corridors echo with emptiness in the evening.
Since each additional cluster represented a large proportionate increase in the study size (and in associated costs) it was necessary to find the proper balance between the need to increase the number of the clusters and its organizational costs.
This is less than one in absolute terms, which indicates that the cellular subscription is income-inelastic, i.e. a unit increase in per capita income elicits a less than proportionate increase in cellular phone subscription.
Since the elasticity coefficient for combined school enrolment was less than one (0.906), it implied that a one percentage point increase in school enrolment could lead to a less than proportionate increase in the Internet usage.
