At airport security, every 25th person gets baggage searched.
systematic random
A pharmaceutical company wants to test the effectiveness of a new drug. Volunteers are assigned randomly to one of two groups. The first group will receive the new drug; the second group will receive a placebo.
simple random
A survey about timekeeping might divide the population by time zone, then take 100 random samples per zone.
stratified random
At a birthday party, teams for a game are chosen by putting everyone's name into a jar, and then choosing the names at random for each team.
simple random
A student council surveys 100 students by getting random samples of 25 freshmen, 25 sophomores, 25 juniors, and 25 seniors.
stratified random
At a bingo game, balls with every possible number are placed inside a mechanical cage. The caller rotates the cage, tumbling around the balls inside. Then, she selects one of the balls at random to be called, like B-12 or O-65.
simple random
While students are lined up for school pictures, a teacher passes out a survey to every 10th student.
systematic random
A principal takes an alphabetized list of student names and picks a random starting point. Every 20th student is selected to take a survey.
systematic random
A team wants to do a research on university students by sampling 30 students from each program.
stratified random
A restaurant leaves a fishbowl on the counter for diners to drop their business cards. Once a month, a business card is pulled out to award one lucky diner with a free meal.
simple random
The company has 800 female employees and 200 male employees so you use random sampling on each group, selecting 80 women and 20 men, which gives you a representative sample of 100 people.
stratified random
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