Statistical Studies
part of a popluation
sample
a procedure by which EVERY member of a population is selected
census
each member of the population is equally likely to be included
random sample
tendency for results to favor one outcome over another
systematic or selection bias
the entire collection of individuals or objects that you want to learn about
population
a number that describes the entire popluation
population characteristic / parameter
divides the population into clusters (subgroups) and then selects a random sample of clusters
cluster sampling
occurs when people choose to participate
voluntary response bias
a study in which the person conducting the study observes characteristics of a sample
observational study
a number that describes a sample
statistic
a sample with subgroups (strata) that appear in the same proportion as population
stratified random sample
occurs when people choose NOT to participate
non-response bias
a study in which the person conducting the study observes how a response variable behaves
experiment
representative sample
the first member of a sample is randomly selected, while the rest are chosen by a specific pattern
systematic sample
response bias
in an experiment the person conducting the study changes this
conditions
a list of ALL members of the population from which sample can be drawn
sampling frame
sample of a given size that is selected in a manner that every possible sample of the defined size is equally likely to be chosen
simple random sample
occurs when the question is stated in a manner that influences the response in a systematic way
wording bias