A researcher recruits participants for an experiment by posting an announcement in the psychology department asking for volunteers. What kind of sampling is being used

The correct answer is non-probability

Non-probabilistic sampling, this type of sampling is used when we do not have access to the complete list of individuals that make up the population (sample frame), so we do not know the probability that each individual will be selected for the sample. The main consequence of this lack of information is that we cannot generalize results with statistical precision.

chavez's example shows that nonviolent protest can work well. it shows that one nonviolent man can stop a mob, which proves chavez's point and persuades people to protest nonviolently.