Stats Flashcards
Discrete data is:
Data with a specific value e.g. age or shoes size
Continuous data is:
Data that can have any value within a specific range e.g. foot length (time can be either)
Population is:
Whole set of the thing you’re interested in
Sample is:
Subset of the thing you’re interested in
Pros and cons of sample (instead of population)
Pros: quicker, faster, cheaper. Cons: might not represent full population, may introduce bias
Sampling frame is:
list of all members of a population
Population parameter is:
numerical value describing a characteristic of the population
Random sampling
Every member of a group has an equal chance of being selected
Pros of random sampling
Free of bias, easy & cheap for small samples & populations. Each sampling unit has a known an equal chance of selection.
cons of random sampling
Not suitable for large samples& populations. sampling frame needed
Systematic sampling
The required elements are chosen at regular intervals from an ordered list
stratified sampling
The population is divided into mutually exclusive strata (e.g men and women), random sample is taken from each
advantages of systematic sampling
Simple and quick to use. suitable for large samples and large populations
advantages of stratified sampling
Sample accurately reflect population structure. proportional representation of group with population
disadvantages of systematic sampling
Sampling frame is needed. bias introduced if sampling frame is not random