large, small
total
population
national
random, representative
clinical, non-clinical

draw, select
a random sample drawn from men aged 35–40

comprise sth, consist of sth
Our sample comprised 250 office workers.

size
A larger sample size yields more reliable data.

survey
group

sample from
The research was based on samples from 29 populations.

sample of
a wide sample of people

blood, faecal/fecal, serum, stool, tissue, urine
DNA, RNA
rock, soil, water
control
biopsy

collect, obtain, take
provide
All the athletes had to provide a urine sample.

analyse/analyze, study, test

contain
show

sample of
samples of tissue

free
They're giving out free samples of the new toothpaste.

book
We looked at sample books to choose the fabric.

sample of
I'd like to see a sample of your work.