The phrase "a substantial sample of" is correct and usable in written English.
It can be used when referring to a significant or considerable portion of a larger group or dataset, often in research or analysis contexts.
Example: "In our study, we collected a substantial sample of participants to ensure the results were representative of the population."
Alternatives: "a significant portion of" or "a considerable amount of".
A substantial sample of upper and lower canines (and lower third premolars) showed that the upper canines of Ardipithecus did not sharpen (hone) as did those of all fossil and modern apes.
"By carrying out detailed scientific tests on a substantial sample of medieval lightweight portable bibles, we have effectively turned what had been regarded as purely art historical objects into new archaeological data," said the director of the research project, Professor Matthew Collins.
A substantial sample of the applicant's writing should be submitted as well as a brief research proposal (approximately 2-5 pages) describing the applicant's research interest.
LFS data between April 1997 and June 2014 were used 10 to obtain a substantial sample of medical graduates on which to base our calculations of average earnings.
We chose inexpensive methods to identify and recruit GPs, relying on an existing database, minor promotion and a letter of invitation, and succeeded in recruiting a substantial sample of GPs.
The present study includes a substantial sample of manic patients and we explored the hypothesis that the pattern of symptoms in manic episodes consist of a multi-dimensional structure which could be used to support distinct clinical subtypes.
An additional strength of the review lay in the breadth of our search, generating a substantial sample frame of 1887 potentially relevant studies (identified via 116 Cochrane reviews) that were screened for eligibility against our inclusion criteria.
Very few articles are available in literature that present failure analysis based on a substantial sample size of real die breakdowns.
Our study was conducted in a substantial sample size of more than 1000 HIV-infected children during the rainy season, a high transmission period of malaria.
A substantial sample frame of 1887 potentially relevant studies (identified via 116 Cochrane reviews) were screened for eligibility against the inclusion criteria.
During our generalization tests, there was a rather substantial sample of subjects that did not receive the visual display component but nonetheless showed high task compliance.
