Five methods of sampling were discussed on The Visual Learner: Statistics and they are the following:
Simple Random Sampling is choosing sample from entire population where every participant or member has equal chance of getting picked. For example, 10 students were needed as participants from population of 20. Random sampling can be done by rolling up 20 papers with writing of “1” or “2” (10 each) placed in a box where students can pull from. The students who randomly picked paper with “1” become the participants.
Systematic Sampling is random selecting a “kth” point or interval. This method is done by retrieving a list of population (not prearranged). Total population is divided by needed sample will give the “k” point. So if there are 100 members in a population and sample of 10 members are needed, 100 ÷ 10 = 10. So the participant at every 10th mark will be chosen as part of the sample. For instance, sampling from population of 1000 patients and 200 patients are needed for the sample, 1000 ÷ 200 = 5. So patient at every 5th interval on the list will be the participant.
Cluster Sampling is grouping a population into clusters then randomly, researcher chooses a cluster. The participants or members of that cluster becomes the sample. For example, children in an elementary school were being surveyed what kind of lunch they prefer to have. Four clusters were needed in the survey. 50 children are clustered into Classroom A, B, C, D, E, F to Z. The clusters (or Classrooms) are then drawn which will be the sample for the survey.
Stratified Sampling is grouping population into at least two groups (called “strata”) that possess same characteristics then sample is randomly taken per stratum. In surveying nurses on career satisfaction, possible participants are grouped according to the field they are in (to group according to characteristics). Population of nurses, per field, for instance include: 17% in psychiatric nursing, 23% medical-surgical nursing, 20% emergency nursing, 10% surgical nursing, 15% pediatric nursing, and 15% outpatient care. Sample is then chosen from every group.
Convenience Sampling is taking results from samples that are most convenient. For example, a Quality Assurance nurse is to perform tracers (mock surveys) to prepare for upcoming Joint Commission survey, instead of interviewing required 30 random staff from six different units (5 st