In the case where the population is large, the random sample group is committed to the list every member of the population may be hard to do or do not, so instead of using the method to pile all the researchers can be random from the group that has been split into the application.solution, and then
การแปล กรุณารอสักครู่..
![](//thimg.ilovetranslation.com/pic/loading_3.gif?v=b9814dd30c1d7c59_8619)