1.1 Population and Samples

What is a population?

The whole set of items that are of interest

What is a census?

Data that is taken from the population

What is a sample?

Data taken from a subset of the population to make a generalisation about the entire population

What is the advantage of a census

Accurate result

What are the advantages of a sample?

• Less time consuming

• Less expensive

• Fewer people have to respond

• Less data to process

What are the disadvantages of a census?

• Time-consuming

• Expensive

• Cannot be used when the testing process destroys the item

• Large quantity of data to process

What are the disadvantages of a sample?

• Data may not be accurate

• The sample may not have enough information about smaller subsets of the population

How does the size of the sample affect any conclusions drawn?

The larger the sample, the more accurate it is

What are individual units of a population known as?

Sampling units

What is a sampling frame?

A list made from sampling units

How to work out the mean?

Add all the numbers and then divide by the amount of numbers

How to work out the range?

Subtract the largest value from the smallest value

How to work out the median?

Order the numbers from smallest to largest and pick the middle number

How to work out the mode?

Count how often each number appears and the number that appears the most is the mode