snowball sampling

Translations
снежный ком (метод отбора)
The researchers used snowball sampling to recruit participants for the study.
Исследователи использовали метод снежного кома для набора участников в исследование.
Definitions
Snowball sampling is a non-probability sampling technique used in research where existing study subjects recruit future subjects from among their acquaintances. This method is particularly useful for accessing hard-to-reach or hidden populations, as it relies on social networks to gather participants.
Words
snowball

adjective
снежный ком
sampling

noun
выборка