Year 1 Stats Flashcards
Population
Whole set of terms which are of interest
Census
A census observes or measures every member of a population
Sample
A sample is a selection of observations taken from a subset of the population which is used to find out information about the population as a whole
What is a Simple Random Sample?
Every sample has an equal chance of being selected
What is systematic sampling?
The required elements are chosen at regular intervals from an ordered list
What is Stratified sampling?
The population is divided into mutually exclusive data and a random sample is taken from each.
What is mutually exclusive data?
Something that can’t happen at the same time
(Males and Females, 2 seperate venn diagrams)
What is Quota sampling?
A researcher selects a sample which reflects the characteristics of the whole population.
What is Opportunity sampling?
Taking people who are available at the time.
What are continuous variables?
A variable that can take any value in a given range
(Height of males in a population - can have an infinite number of heights/solutions) - 165.3324, 175.4445, 193.98)
What are discrete variables?
A variable that can only take specific values in a given range
(Rolling a dice - can only have 6 possible solutions)
How do you do stratified sampling?
Disadvantage of simple random sampling
Not good when sample is too large
Disadvantage of Systematic sampling
Can be bias if the sampling frame is not random
Disadvantage of stratified sampling?
Population must be split into distinct data.
