Block
A group of experimental units or subjects that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.
Block design
The random assignment of units to treatments carried out separately within each block
Treatment
Condition imposed on a an experimental unit or subject
Design
Refers to the choice of treatments and the manner in which the experimental units or subjects are assigned to the treatments
Confounding
The effects of a treatment with other influences, such as lurking variables
Randomization
The use of chance to assign subjects to the treatments
Bias
Systematic favortism in experiments
Replication
Reduces chance variation in results by imposing each treatment on many units
Statistically significant
An observed effect so large that it would rarely occur by chance
Double blind experiment
An experiment where neither the subjects nor the people in contact with them know which treatment the subject recieves
Matched pairs
A form of blocking that compares two treatments
Comparison
The simplest form of control
Principle of Experimental Design
States that control, randomization, and replaction are the basic principles of statistical design in an experiment
Factors
The explanatory variable in an experiment
Level
The combining of specific values of each factor in an experiment that studies the joint effect of several factors to form a treatment
Placebo effect
The response to a dummy treatment
Placebo
A dummy treatment
Control Group
The control of outside variables and there effects on the outcome
Lack of realism
When the subjects, treatments or setting in an experiment dont realistically duplicate the conditions we want to study.