1.1 Populations and samples

Question 1

What is a population?

Answer 1

» The whole set of items that are of interest

Question 2

What is a census?

Answer 2

» Observes or measures every member of the population

Question 3

What is a sample

Answer 3

» A selection of observations taken from a subset of the population which is used to find out information about the population as a whole

Question 4

What are the advantages of a census?

Answer 4

» Should completely give accurate results

Question 5

What are the disadvantages of a census?

Answer 5

» Time-consuming and expensive
» Cannot be used when testing process destroys the item
» Hard to process large quantitiy of data

Question 6

What are the advantages of a sample?

Answer 6

» Less time-consuming and expensive than a census
» Fewer people have to respond
» Less data to process than in a census

Question 7

What are the disadvantages of a sample?

Answer 7

» The data may not be accurate
» The sample may not be large enough to give information about small sub groups of the population

Question 8

What are sampling units?

Answer 8

» Individual units of a population

Question 9

What is a sampling frame?

Answer 9

» Often sampling units of a population are individually named or number to form a list called a sampling frame

Question 10

What will you need to do if the population is very varied, not uniform?

Answer 10

» You need a larger sample size

Question 11

What happens with a greater sample size?

Answer 11

» More accurate
» More resources needed