Population
The entire collection items we want information about
Sample
A subset of individuals or items from which we actually collect data
Census
A sample survey that attempts to include the entire population in the sample
Convenience sample
Choosing individuals from the population who are easy to reach
Voluntary response sample
A sample consisting of people who choose themselves by responding to a general invitation
Simple random sample
A subset of individuals chosen in such a way that every group of n individuals in the population has an equal chance to be selected as the sample
Random sampling
Involves using a chance process to determine which members of a population are included in the sample
Stratified sample
Classifying the population into homogeneous subgroups and then choosing a separate SRS in each subgroup for the sample
Cluster sample
Classifying the population into heterogenous groups and then choosing an SRS of the groups. All individuals in the selected groups are in the sample.
Systematic sample
The elements of the population are put into a list and every k-th element in the list are chosen for the sample
Random assignment
The experimental units are assigned to treatments using a chance process
Observational study
Observes individuals and measures variables of interest but does not attempt to influence the responses
Sample survey
The type of observational study that uses an organized plan to choose a sample that represents some specific population
Experiment
Directly imposes some treatment on individuals to measure their responses
Bias
Consistently underestimates or consistently overestimates the value you want to know
Parameter
A number that describes some characteristic of the population
Statistic
A number that describes some characteristic of a sample
Simulation
An effective tool for finding probabilities of complex events by imitating chance behavior