Opportunity sampling is a non-probability sampling technique where participants are selected based on their availability and accessibility at the time of the study.
What is random sampling?

Random sampling is a method of selecting a sample from a population in which each individual has an equalchance of being chosen.
What is volunteer sampling?

Sampling method where participants are selected based on their willingness to participate.
What is systematic sampling?

Systematic sampling is a sampling method where every nth element in a population is selected to be part of the sample. For example, every 4th person.
What is stratified sampling?

Stratified sampling is a sampling technique where the population is divided into distinct subgroups, and a randomsample is taken from each subgroup in proportion to its size.