Because of the method of random selection of foreign tourists who come to take advantage of Spa in Krabi. The number of 200 people to a test sample of customer satisfaction in the service. Foreign tourists all have equal opportunity to be selected to do this quiz.
Because the randomized foreign tourists have visited the spa in Krabi, a sample of 200 students to quiz the satisfaction of the spa. Foreign tourists, everyone has an equal chance of being selected to do the test.