a study that observe and record behaviors
researchers impose a treatment on the subjects
W/ an experiment, there must be an explanatory response
Difference between an observational study and an experiment
variable that's manipulated
variable you measure; what you want to know
what you did your experiment on; when talking about people use 'subjects'
the variable of interest (explanatory variable)
Factors of the experiment
measure of a particle factor
levels of the experiment
subjects are assign a baseline treatment to use as a comparison
random assignment of subjects
perform the experiment on more than one subject
simplest form of design; similar to simple random sampling; every sample of size (n) has an equal chance of being picked.
Completely randomized design
subjects are group before the experiment begins to reduce variation; similar to stratified sampling
completely randomized block designs
similar to paired t-test; special king of block; each subject gets both treatments.
matched pairs design
to control the factors you can see;
The purpose of blocking is?
helps balance the ones you cannot see
The purpose of randomization?
when results are too large to attribute to chance
when subject respond to a placebo as if they've gotten the treatment
either the subject or the researcher does not know what treatment is given
both of the subject and the researcher do not know which treatment is given.
a variable that's there before you begin your study that you were not aware of
you can not separate the effects of the explanatory variable from the other influences on the response
Completely randomized and block designs
Two types of experimental design are
control, randomization, and replication
What are the three principles of experimental design