Experiments & Observational Studies Vocab

Double-blind

Neither the subjects nor the people who have contact with them know which treatment a subject has received

Subjects

People who are studied

Treatment

The process or intervention applied to randomly assigned experimental units

Control Group

Experimental units assigned to a baseline treatment level

Completely Randomized

Type of experiment in which all experiment units have an equal chance of receiving any treatment

Single-blind

When either the subjects or the people who have contact with them do not know which treatment a subject has received

Placebo

Treatment known to have no effect, administered so that all groups experience the same conditions

Factor

Variable whose levels are controlled by the experimenter

Statistically Significant

When an observed difference is too large to believe that it is likely to have occurred naturally

Matched Study

Type of study in which subjects who are similar in ways not under study may be grouped together and then compared with each other on the variables of interest

Observational Study

Study based on data in which no treatments have been assigned to subjects

Confunded/Confouding

When the levels of one factor are associated with the levels of another factor so their effects cannot be separated

Experimental Units

Individuals on which an experiment is done

Block

When groups of experimental units are similar, they are gathered into these groups

Placebo Effect

The tendency of many human subjects to show a response even when administered a placebo

Prospective Study

Observational study in which subjects are followed to observe future outcomes

Randomized Experiment

Study in which subjects are randomly assigned to treatments

Lurking Variable

Aspects of the experiment that we know may have an effect on the response, but that are not the factors being studied

Retrospective Study

Observational study in which subjects are selected and then their previous conditions or behaviors are determined

Levels

Specific values that the experimenter chooses for a factor