## What is Statistics? Exercise

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 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. b A sample which does not accurately represent the group from which it is taken is called arandom sample. c A census involves surveying every member of a population. d If a sample is taken and it is not random, any conclusions are likely to be biased. e A census is held every three years in Australia and New Zealand? f 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. g Bias in a survey can be avoided by selecting random samples. h 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. i In a random sample every member of the population has an equal chance of being selected. j A survey which covers every member of a population is called an election.