Ap. Statistics 5.2

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.