1.1: Population and Samples Flashcards
What does this chapter contain?
- Understand population, sample, census and comment on the advantages and disadvantages of each
- Understand the advantages of simple random, systematic sampling, Stratified sampling, quota sampling, and opportunity sampling
- Define qualitative, quantitative, discrete, continuous data and understand grouped data
- Understand the large data set and how to collect data from it, identify types of data and calculate simple statistics
What is a population?
A population is the whole set of items that are of interest
What is a census?
A census observes or measures every member of a population.
What is a sample?
A sample is a selection of observations taken from a whole subset of the population which is used to find out information about the whole population as a whole.
What is the advantage of a census?
It should give a completely accurate result.
What is the advantage of a sample?
- Less time consuming and less expensive than a census
- Fewer people have to respond
- Less data to process than in a census
What are the disadvantages of a census?
- Time consuming and expensive
- Cannot be used when the testing process destroys the item
- Hard to process large quantity of data
What are the disadvantages of a sample?
- The data may not be as accurate
- The sample may not be large enough to give information about small subgroups of the population
What are sampling frames?
Individual units of a population numbered or named to form a list.
What are sampling units?
Individual units of a population
How does the size of a sample affect affect conclusions?
- Generally, the larger the sample, the more accurate it is
- If the population is very varied, you need a larger sampling frame than if the population were uniform.
What affects the size of a sample?
- The accuracy required
- Available resources
