The phrase "a supplementary sample of" is correct and usable in written English.
It can be used when referring to an additional or extra sample that complements or adds to a primary sample in a study or analysis.
Example: "In our research, we collected a supplementary sample of data to ensure the accuracy of our findings."
Alternatives: "an additional sample of" or "a complementary sample of".
Because the NLTCS has been repeatedly replenished during each wave with a supplementary sample of 65 to 69 year-olds to replace those who died between surveys, it continues to be representative of the entire elderly Medicare beneficiary population.
For these reasons, many of the baseline study population had opted to remain in displacement, or had not yet been drafted in to the process of return migration by the government – hence the need for a supplementary sample of return migrants at follow-up.
The follow-up (COMRAID-R) was carried out in 2012, one year later, and involved tracing and re-interviewing previous participants as well as recruiting a supplementary sample of return migrants from this particular population who were now resident in Mannar district, the original location from where they had been displaced.
The prevalence in the supplementary sample of return migrants was comparably low which supports a genuine reduction in prevalence since both groups were systematically sampled with 100% participation.
For the purpose of data analysis, baseline participants who had completed return migration were grouped together with the supplementary sample of return migrants, as they were too small in size to analyse separately.
Participation at baseline and in the supplementary sample of return migrants was 100%, attained because of the careful building up of a close rapport with the IDP community, demonstrating the feasibility of such research among difficult to reach, vulnerable groups in resource-poor post-conflict settings.
A full presentation of pack images used is included in online supplementary appendix A and a sample of pack presentation and questions used is included in online supplementary appendix B. For each pack pair, several questions were asked related to their perception of the packs.
Supplementary samples from 157 specimens of arctic fungi deposited at the Natural History Museum, University of Oslo (O) were also included in the study.
The aim of the present study was to assess the validity and usefulness of a new measure to assess disability (see electronic supplementary material) in a sample of patients with chronic daily headache.
Reasons for aspirin use were assessed in 1993 by a supplementary questionnaire sent to a random sample of 211 participants, who reported taking aspirin from 1986 to 1990.
Templates for probes were amplified (primers listed in supplementary table S3, Supplementary Material online) from a mixed sample of VNO cDNA from male and female corn snakes.
