Chapter 13 Flashcards
Observational study
a study based on data in which no manipulation of factors has been employed
Retrospective study
an observational study in which subjects are selected and then their previous conditions or behaviors are determined
Prospective study
an observational study in which subjects are followed to observe future outcomes
Experiment
An experiment manipulates factor levels to create treatments, randomly assigns subjects to these treatment levels, and then compares the responses of the subject groups across treatment levels
Random assignment
To be valid, an experiment must assign experimental units to treatment groups at random
Factor
a variable whose levels are manipulated by the experimenter
Response
a variable whose values are compared across different treatments
Experimental units
individuals on whom an experiment is performed
Level
the specific values that the experimenter chooses for a factor
Treatment
the process, intervention, or other controlled circumstance applied to randomly assigned experimental units
Principles of experimental designs
control, randomize, replicate, block
Statistically significant
when an observed difference is too large for us to believe that it is likely to have occurred naturally, we consider the difference to be statistically significant
Control group
the experimental units assigned to a baseline treatment level, typically either the default treatment, or a null, placebo treatment
Blinding
any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups
Single blind
when every individual in either of these classes is blinded