1. A survey of parents is being held by the Principal of a secondary school to find out whether to build a new gymnasium.

Comment on the follow methods suggested to select a sample of parents to take part in a survey.

a. The parents of every student at the school is posted a questionnaire to fill in.

b. The parents of all Year 12 students at the school are asked to take part.

c. A sample of 30 first year students are chosen at random.

d. The Principal invites parents to a meeting and the parents who turn up are asked their opinion.

e. The students names are listed alphabetically and every 10th student is selected and their parents are sent a questionnaire.

2. True or false?

A sample taken for a survey where every member of a population has an equal chance of being chosen is said to be a random sample.
A sample which does not accurately represent the group from which it is taken is called arandom sample.

A census involves surveying every member of a population.


If a sample is taken and it is not random, any conclusions are likely to be biased.

A census is held every three years in Australia and New Zealand?
The first 100 students to arrive at school are asked their opinions of the school! 
The results of this survey be likely to be biased.

Bias in a survey can be avoided by selecting random samples.

A sample for a survey on the study habits of all students in a secondary school is taken by selecting every 10th person on the alphabetical school roll. This is a random sample.

In a random sample every member of the population has an equal chance of being selected.

A survey which covers every member of a population is called an election.