Probability Sampling
The most basic probability method, often described as "drawing names from a hat," where every individual in the population has an equal chance of being selected.
What is Simple Random Sampling?
This sampling method is based on the researcher's ease of access, such as surveying students who are conveniently available in the library.
What is Convenience (or Opportunity) Sampling?
A teacher distributes a checklist to students to record how often they participate in group work.
Survey and Questionnaire
Recording the number of steps taken each day.
Quantitative
This random sampling technique involves selecting a random starting point and then choosing every nth person from a list of the population.
What is Systematic Sampling?
A non-probability method where participants are recruited through referrals from existing participants, often used for hard-to-reach populations.
What is Snowball Sampling?
A scientist conducts repeated trials to measure how different fertilizers affect plant growth.
Experiment
Identifying the brands of mobile phones used by students.
Qualitative
A researcher divides the school population by grade level and then randomly selects students from each grade to ensure that each group is proportionately represented.
What is Stratified Sampling?
Using student volunteers in a psychology department to take part in a study is a form of sampling that is fast and cheap but may produce this kind of unrepresentative sample.
What is Convenience sampling?
A nutritionist observes how children choose food during lunch at a public school.
Observation
A psychology department at a large university randomly selects three psychology classes and then studies every student in those chosen classes.
What is Cluster Sampling?
A type of non-probability sampling where a researcher ensures there is a proportional representation of certain groups by recruiting participants until a predetermined number for each group is met.
What is Quota Sampling?
A teacher closely observes how students interact during a group math activity.
Observation
A health worker chooses participants based on age group, ensuring equal numbers from teens, adults, and seniors
What is Stratified Sampling?
This qualitative sampling method involves the researcher continuing to recruit new participants not to increase representativeness, but to refine an emerging theory by finding cases that challenge or confirm their ideas.
What is Theoretical Sampling?
A school principal reviews disciplinary records from the past school year.
Case Study