1. A survey is being held to find out whether students at a secondary school of 400, think the school rules should be changed.
Which of the following methods would produce a random sample of size 20.
Give a reason for each answer and state whether you think the results would be biased.
a. You go to the detention room and ask the first 20 people you see there.
b. You go to the front office and get an alphabetical list of all of the students at the school and pick every 20th student from the list.
c. You pick the first 20 students born in May from the list.
d. You go to the Year 13 assembly and ask 20 students their views.
2. A survey company rings people up during the day to get their opinions on a new brand of breakfast cereal.
Give reasons why this method of questioning may not give a random sample of people.
3. The organisers of a political poll ring up 250 people in each of the main centres, Sydney, Melbourne, Brisbane, Canberra, Adelaide and Perth. They are trying to predict the outcome of an upcoming election. Why might their prediction not be accurate?
4. The managing director of a company wants to find out whether the workers want the chance to work more overtime. There are a number of ways she can find out. Discuss the advantages and disadvantages of each method listed below.
a. She goes to one of the company's departments and asks everyone there.
b. She holds a voluntary meeting after work and asks everyone who turns up
c. She writes to everyone and asks them to write back to her with their views
d. She interviews every worker individually and asks them.
e. She makes a list of all of the workers and interviews every 5th worker on the list.
