The phrase "a subsample of one" is correct and usable in written English.
It can be used in statistical or research contexts to refer to a sample that consists of a single observation or data point.
Example: "In this study, we found that the results were based on a subsample of one, which limits the generalizability of our findings."
Alternatives: "a single data point" or "one observation".
A subsample of one-third of the households was selected to conduct HIV testing for eligible women aged 15 49 years.
In the National Health and Nutrition Examination Survey (NHANES), a subsample of one-third of participants ≥ 12 years of age was selected and was measured for the concentrations of OC pesticides or their metabolites in blood in each biannual data cycle.
From a subsample of about one quarter of the study population, data on vaccination coverage with all recommended vaccinations at age 1 year was available (17).
These comparisons were conducted on a subsample of five runners on two study days, one chosen to represent a day with high ambient sulfate levels and the other a day with low ambient sulfate levels.
Urinary BPA and triclosan were measured in a random subsample of one-third of participants > 6 years of age (n = 5,250).
PAH metabolites were measured in spot urine samples obtained from a random subsample of one-third of subjects ≥ 6 years of age.
Urine cadmium was measured only in a randomized subsample of one-third of the 1999 2004 NHANES population (n = 2,867 in our study population).
On a subsample of 30 trees per species (one tree per plot), detailed non-destructive branch measurements were performed, yielding data for 555 oak and 438 beech branches.
Following Beets (1977), specific leaf area was determined from measurements of fascicle diameter, length, and dry mass based on a subsample of 20 fascicles from both year-one and year-two age classes.
72, 78 In one, a subsample of patients with partial seizures taking part in a randomized, double-blind, controlled study comparing the cognitive effects of TPM and LTG, was administered a computerized task measuring scanning, divided attention, and effective field of view (via the Performance On-Line, or POL).
