Ingrid is working on a project for her psychology class. She is having trouble getting participants for her study. Therefore, she has begun to ask those who do participate for names of other individuals who might be willing to participate. What type of nonprobability sampling procedure is Ingrid using

Snowballing

Explanation:

Snowball sampling often referred to as chain-referral sampling is a method of sampling used in social statistic, which is defined as a non-probability sampling technique whereby the samples have characteristics that are rare to find. It is characterized by scenario in which the existing subjects provide referrals to recruit samples required for a research study.

Hence, in this case, Ingrid making use of Snowballing non probability sampling technique, since she is using those interested to be the subjects of the study to find more of the subjects to use as sample of the research.