Population and samples Flashcards
What is a population?
A collection of individual people or items
What is a census?
A survey of an entire population
Give two advantages of taking a census
- It is unbiased
* It gives an accurate answers
Give three disadvantages of taking a census
- It takes a long time to do
- It is costly
- It is often difficult to ensure that the whole population is surveyed
What is sampling?
The process of only surveying a subset of an entire population
What is a sampling unit?
An individual member of a sample
What is a sampling frame?
A list from which a sample is drawn
Give three advantages of sampling
- It is cheaper than taking a census
- It is quicker than taking a census
- It is advantageous where the testing of items results in their destruction, i.e. testing the lifetime of light bulbs
Give two disadvantages of sampling
- Different samples may vary greatly
* The sample may be selected with bias
What is a simple random sample?
A sample taken such that every possible sample of size n has an equal chance of being selected
What is a statistic?
A quantity calculated solely from the observations in a sample
What is a sampling distribution?
How the various possible values of a statistic are distributed
