A researcher selects a sample in this way. The researcher paints numbers on 100 ping-pong balls and paints half of the balls blue and half of them green. The researcher puts the blue half onto a large tray and the green half onto another large tray. Then the researcher mixes each tray of balls and trains a dog to bring 10 balls from each tray to the researcher, gently and systematically, one at a time. What type of sample is this?

Question

Quizplus · Accepted Answer

The sample is stratified random because the population (ping-pong balls) is divided into two strata (blue and green balls) and random samples are taken from each stratum.

A Researcher Selects a Sample in This Way