Statistics definitions Flashcards
Census
Observes and measures every member of a population
Sample
A selection of observations taken from a subset of the population which is used to find out information about the population as a whole
Adv/disadv of census
Completely accurate
Time consuming/expensive
What are the individual units called?
Sampling units
What is the list of sampling units called?
Sampling frame
adv/disadv of sample
less time consuming
May not be accurate or large enough
What is a random sample
Group where every sampling unit has an equal chance of being chosen
What is systematic sampling?
Where the required elements are chosen at regular intervals from an ordered list
What is stratified sampling?
Where the population is divided into mutually exclusive strata and a random sample is taken from each
What is the equation for stratified sampling?
Number in stratum/number in population X overall sample size
Adv/disadv of random sampling
Unbiased, easy and cheap
not suitable with large sample size, needs sampling frame
Adv/disadv of systematic sampling
Simple and suitable for large samples
Needs random sample frame
Adv/disadv of stratified sampling
Accurately reflects population structure and guarantees proportional representation
Must has distinct strata
Quota sampling
Sample is selected that reflects the characteristics of a whole population
Opportunistic sampling
Sample is taken from people who are available at the time of the study and fit the criteria
