The phrase "ascertain what proportion" is correct and usable in written English.
It can be used when you want to determine or find out the specific percentage or fraction of something in a given context.
Example: "In order to improve our marketing strategy, we need to ascertain what proportion of our customers prefer online shopping over in-store purchases."
Alternatives: "determine the percentage" or "find out the fraction".
The primary purpose of this study was to ascertain what proportion of the body of published literature in pediatric urology is represented by randomized controlled trials.
One simple way of measuring the variability of a gene locus is to ascertain what proportion of the individuals in a population are heterozygotes at that locus.
The NHAMCS is not designed to collect information about chronic conditions, and thus we were unable to ascertain what proportion of our cases were "breakthrough seizures" occurring in patients who already had a diagnosis of epilepsy, versus acute symptomatic seizures, versus first-time unprovoked seizures.
Such study designs cannot ascertain what proportion of the recovery rates can be accounted for by factors such as spontaneous remission over time.
The aim of the present study was to ascertain what proportion of general surgical patients are at high risk of postoperative death.
The observational study design cannot ascertain what proportion of the recovery rates can be accounted for by factors such as spontaneous remission over time.
Our objectives were to determine what proportion of patients think prognostic information is important, the reasons they give for (not) why they feel prognostic information is important, and to ascertain how often patients feel that their prognosis is discussed in the consultation.
We will continue to speak to the victims to ascertain what this ascertained.
It is harder to ascertain what the order would do than what it would not do.
When he visited the bookstore, agents got close enough to ascertain what books caught his interest.
Financial advisers use different methods to ascertain what their clients can comfortably afford.
