The airline company from Exercise 4, which is interested in the opinions of its frequent f lyer customers about its proposed new routes, has decided that different types of customers might have different opinions. Of their customers, 50% are silver level, 30% are blue, and 20% are red. The researchers first compile separate lists of silver, blue, and red members and then randomly select 5000 silver members, 3000 blue members, and 2000 red members to email. What kind of sampling method have they used?

Data from in exercise 4 

An airline company is interested in the opinions of its frequent flyer customers about its proposed new routes. Specifically, pollsters want to know what proportion of flyers plan to use one of the airline’s new hubs in the next six months. The pollsters take a random sample of 10,000 from the database of all frequent flyers and send them an email message with a request to fill out a survey in exchange for 1500 air miles.

a) What is the population?

b) What is the sampling frame?

c) What is the population parameter of interest?

d) What sampling method is used?