Influential Observation
A point in a scatter plot that changes the regression line
Causation
Changes in x cause changes in y
Extrapolation
When you predict for a value outside of the domain
Confounding
effect of y on x, mixed up with effects on y with another variable, z
Common Response
x and y respond to changes in unobserved variables
Lurking Variable
variable that has an important effect on the relationship among variables in the study, but not included
Observational Study
Does not attempt to influence responses; just observing
Experiment
Deliberately imposes some treatment on individuals in order to observe their response
Population
Entire group of individuals to be studied
Sample
Subset of studied population
Experimental Units
Individuals on which an experiment is done
Subjects
Units are people
Placebo Effect
Dummy treatment with no physical effect
Treatment
Specific experimental condition applied to units
Control Group
Group of subjects with no treatment/given a placebo
Statistically Significant
Observed effect is too large to attribute plausibly to chance
Double Blind
Neither subjects/people who have contact with them know which treatment a subject recieves
Block Design
Random assignment of units to treatments is carried out within each block
Matched Pairs
2 treatments:
- match subjects (pairs)
- each subject gets both treatments in random order
(blocking)
