Professor Lilli Gans wishes to study the relationship between a person's zodiac sign and his or her political opinions. She obtains the birthdays of all 816 students enrolled in her Astrology 101 course. Then she uses a random digits table to choose 10 students from each of the twelve zodiac signs. For example, students born from March 21 until April 19 have the Aries zodiac sign, and Professor Gans chooses 10 Aries students at random. She uses a different part of the table of random digits to choose students having each sign. After obtaining her sample, Professor Gans has the selected students fill out a questionnaire.
Professor Gans has obtained a

Question

Quizplus · Accepted Answer

The sampling method used is a stratified random sample, where the strata are students with different zodiac signs. This is because the professor intentionally chooses to sample from each zodiac sign separately, using a different part of the random digits table for each sign. The purpose of the study is to study the relationship between zodiac signs and political opinions, so zodiac sign is the main variable of interest and is used as the basis for stratification.

Professor Lilli Gans Wishes to Study the Relationship Between a Person's