Sampling Techniques

A student council surveys 100 students by getting random samples of 25 freshmen, 25 sophomores, 25 juniors, and 25 seniors.

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.

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.

A survey about timekeeping might divide the population by time zone, then take 100 random samples per zone.

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.

A principal takes an alphabetized list of student names and picks a random starting point. Every 20th student is selected to take a survey.

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.

While students are lined up for school pictures, a teacher passes out a survey to every 10th student.

A team wants to do a research on university students by sampling 30 students from each program.

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.

At airport security, every 25th person gets baggage searched.